CN111144761A

CN111144761A - Railway route selection method based on typical underground geological disaster risk evaluation

Info

Publication number: CN111144761A
Application number: CN201911379759.4A
Authority: CN
Inventors: 李天斌; 马俊杰; 曾鹏; 吴君艳
Original assignee: Chengdu Univeristy of Technology
Current assignee: Chengdu Univeristy of Technology
Priority date: 2019-12-27
Filing date: 2019-12-27
Publication date: 2020-05-12

Abstract

The invention discloses a railway route selection method based on typical underground geological disaster risk evaluation, which is characterized in that an analytic hierarchy process is adopted to establish an evaluation model of easiness of high ground temperature, rockburst and large deformation by screening influence factors of 3 types of disasters including high ground temperature, rockburst and large deformation; comprehensively considering the influence of each underground disaster on the railway engineering, and judging the danger of the underground disaster through the characteristics of railway route selection and each underground geological disaster; by integrating market research and similar engineering experience, the unit economic loss of railway engineering caused by disaster happening under various regions is determined by adopting an analogy estimation algorithm; and finally, integrating 3 types of disasters, and constructing a railway route selection economic loss evaluation system for the comprehensive risk evaluation of the underground geological disasters by adopting a comprehensive risk measurement method. The method solves the problems that the railway route selection can not comprehensively analyze and evaluate uncertain factors such as environment, economy and the like, a risk assessment method and a route selection theory aiming at multi-source underground geological disasters are lacked, and risk factor events in railway engineering construction are various and are difficult to accurately judge.

Description

Railway route selection method based on typical underground geological disaster risk evaluation

Technical Field

The invention belongs to a railway construction route selection method, and particularly relates to a railway route selection method based on typical underground geological disaster risk evaluation.

Background

At present, with the implementation of deep development strategy in the western regions of China, a series of important railway engineering is to be implemented, such as Sichuan railway, Dian railway and the like. The geological environment of these areas is very complicated, and railway line walks and often uses the tunnel as the main, and is mostly buried deeply tunnel of growing up, and the calamity is easy to send out. Particularly, in western mountainous areas with complex geological environments, when a tunnel passes through a high ground stress area, if the tunnel is soft rock, the risk of large deformation disasters exists, and if the tunnel is hard and brittle surrounding rock, the risk of rockburst disasters exists; when the tunnel passes through the geothermal abnormal area, the risk of high geothermal disasters occurs. In view of the fact that the disasters in the tunnel engineering directly threaten the safety of constructors and equipment, the construction period is slowed down, and the engineering cost investment is increased. Therefore, in the line selection stage, reasonable and accurate evaluation on the underground disasters is necessary, so that reference opinions are provided for railway line comparison and selection.

At present, researchers at home and abroad do more work and obtain certain results in the aspects of road route selection, risk assessment and underground geological disaster risk assessment, but the research on optimizing railway routes based on the risk assessment of underground geological disasters is less, and a more accurate quantitative risk assessment model needs further deep research. Therefore, when a railway crosses a poor geological region, quantitative risk assessment of the route design work is particularly important, especially in western railway engineering with great strategic and economic significance. Through carrying out risk evaluation research on the underground geological disasters of the railway comparison and selection route, a relatively reasonable recommended route scheme can be selected, so that the engineering safety risk is reduced, the serious underground geological disaster hidden danger is avoided, the construction period is shortened, the construction cost is reduced, and the maintenance cost in the operation period is reduced. The research result can be directly applied to actual engineering, and can also provide guidance and regulation revision accumulation data for other similar engineering route selection designs.

Researchers at home and abroad have done much work and achieved certain achievements on the aspects of road, route selection, risk assessment and underground geological disaster (high ground temperature, rockburst and large deformation) risk assessment. However, the research for optimizing the railway line based on the risk assessment of high ground temperature, rock burst and large deformation disaster is less, and the research significance of the existing defects and papers is mainly the following aspects:

1. at present, the road route selection in China mainly comprehensively considers technology, economy and environment and selects a more reasonable and economical optimal route scheme. The circuit optimization method is limited to the experience and technical level of designers to a certain extent, is easily influenced by subjective factors of the designers, and cannot comprehensively analyze and evaluate the influence of uncertain factors such as environment, economy and the like.

2. In the railway route selection stage, due to the lack of data, the risk assessment difficulty for high ground temperature, rock burst and large deformation disasters is high, and the research is less. At present, in the line selection stage, the risk assessment of high ground temperature, rock burst and large deformation disasters is usually carried out simply by experts and technicians according to experience, and systematic risk assessment research is not carried out.

3. At present, the risk assessment aiming at a single underground geological disaster in the construction period has certain research, but a unified risk assessment method and a line selection theory aiming at a multi-source underground geological disaster are lacked.

4. Risk factors and risk events in railway engineering construction are numerous and difficult to judge accurately, most of current researches on railway route selection based on risk assessment only predict the occurrence probability or severity of each risk event, and a systematic loss quantification model capable of reflecting actual engineering conditions is not established, namely, the risk probability is converted into more visual economic loss.

Disclosure of Invention

The invention provides a railway route selection method based on typical underground geological disaster risk evaluation, which solves the problems that the railway route selection cannot comprehensively analyze uncertain factors such as evaluation environment, economy and the like, a unified risk evaluation method and a route selection theory aiming at multisource underground geological disasters are lacked, and risk factors and risk events in railway engineering construction are various and are difficult to accurately judge.

The technical scheme adopted by the invention is as follows:

a railway route selection method based on typical underground geological disaster risk evaluation comprises the following steps:

s1, evaluation of susceptibility: screening disaster types of key influence factors, and respectively determining the weight of each disaster type induction factor by adopting an analytic hierarchy process; respectively constructing an susceptibility evaluation system of each disaster type according to the weight of each disaster type inducing factor; corresponding the basic data of the disaster section to an evaluation system to obtain an evaluation value of easiness in occurrence, and corresponding the evaluation grade to a specified probability grade to obtain the easiness in occurrence H of the disaster section;

s2, determining economic loss V of each linear meter of railway tunnel engineering caused by disaster of each disaster type, and determining the length B of the disaster section;

s3, risk assessment: the probability of threatening the construction of the tunnel after the underground geological disaster occurs is represented by the danger degree D; judging the risk degree D of damage of each disaster type to the railway tunnel engineering according to the disaster type;

s4, determining economic losses of each disaster type to the railway by adopting a comprehensive risk measurement method, wherein the comprehensive risk measurement method is to combine the susceptibility H, the risk D, the length B of each disaster type and the economic losses V of each linear meter of the railway disaster-bearing body to construct a risk evaluation model of each disaster type: economic risk value R of disaster section_j＝H*D*B*V；

S5, calculating the total economic risk value of the line scheme: the total economic risk value of the line scheme is equal to the algebraic sum of the economic risk values of all underground geological disaster points along the line scheme, namely

Wherein j is 1,2, …, m, m is N^*。

Further, the disaster types include high ground temperature, rock burst, and large deformation.

Further, the method for evaluating the vulnerability in the risk evaluation of the high ground temperature comprises the following steps:

s101, determining high ground temperature risk inducing factors, wherein the inducing factors serve as high ground temperature disaster inducing factors, and the high ground temperature disaster inducing factors comprise hot spring temperature, tunnel burial depth, heat source and line distance and fault and line distance;

s102, the high-ground-temperature disaster-causing factors are used as high-ground-temperature risk assessment indexes, the importance of each criterion layer relative to a target layer is judged through a pairwise comparison method by adopting a 1-9 scale method, and therefore a high-ground-temperature risk judgment matrix is established;

s103, calculating the weight of each evaluation index by adopting a maximum characteristic value method according to the high-ground-temperature risk judgment matrix, and judging that the high-ground-temperature risk judgment matrix is reasonably constructed through consistency check acceptance; determining a hot spring temperature weight, a tunnel burial depth weight, a heat source and line distance weight and a fault and line distance weight;

s104, multiplying the corresponding weight of each index by 100 to obtain the maximum evaluation value of each index, and determining the susceptibility evaluation value of each index by adopting the maximum evaluation value of each index to refer to the refinement range grade of each index in the tunnel high-ground-temperature evaluation system table; obtaining a total evaluation value of high ground temperature susceptibility according to the susceptibility evaluation values of the indexes; dividing the susceptibility grade according to the total value of the high-ground-temperature susceptibility evaluation, and corresponding the accident occurrence probability grade division standards one by one; and obtaining the probability grade of the easiness in occurrence, and taking the central value of the corresponding probability value, wherein the central value of the corresponding probability is the high geothermal easiness in occurrence.

Further, the method for evaluating the susceptibility in the risk evaluation of rock burst is as follows:

s201, determining rock burst influence factors, and taking the rock burst influence factors as rock burst disaster-causing factors, wherein the rock burst disaster-causing factors comprise lithologic conditions, ground stress conditions, geological structure conditions and surrounding rock conditions; the lithological condition is rock strength;

s202, using the rock burst disaster-causing factor as a rock burst risk assessment index, judging the importance of each criterion layer relative to a target layer by a pairwise comparison method by adopting a 1-9 scale method, and establishing a rock burst risk judgment matrix;

s203, calculating the weight of each evaluation index by adopting a maximum characteristic value method according to the rock burst risk judgment matrix, and judging that the rock burst risk judgment matrix is reasonably constructed through consistency inspection acceptance; determining lithology condition weight, ground stress condition weight, geological structure condition weight and surrounding rock condition weight;

s204, multiplying the corresponding weight of each index by 100 to obtain the maximum evaluation value of each index, and determining the susceptibility evaluation value of each index by referring to the refinement range grade of each index in the tunnel rock burst susceptibility evaluation table by using the maximum evaluation value of each index; obtaining a total evaluation value of the rock burst susceptibility according to the susceptibility evaluation values of the indexes; and dividing the probability grade according to the total rock burst probability evaluation value, corresponding to the accident occurrence probability grade division standard one by one to obtain the rock burst probability grade, and taking the central value of the corresponding probability value, wherein the central value of the corresponding probability is the rock burst risk probability.

Further, the evaluation method for the susceptibility in the risk evaluation of large deformation is as follows: .

S301, determining large deformation influence factors, and taking the large deformation influence factors as large deformation disaster-causing factors, wherein the large deformation disaster-causing factors comprise lithologic conditions, ground stress conditions, geological structure conditions and surrounding rock conditions; the lithological condition is rock strength;

s302, taking the large deformation disaster-causing factor as a large deformation risk evaluation index, judging the importance of each criterion layer relative to a target layer by a pairwise comparison method by adopting a 1-9 scale method, and establishing a large deformation risk judgment matrix;

s303, calculating the weight of each evaluation index by adopting a maximum characteristic value method according to the large deformation risk judgment matrix, and judging that the large deformation risk judgment matrix is reasonably constructed after the evaluation indexes are acceptable through consistency inspection; determining lithology condition weight, ground stress condition weight, geological structure condition weight and surrounding rock condition weight;

s304, multiplying the corresponding weight of each index by 100 to obtain the maximum evaluation value of each index, and determining the susceptibility evaluation value of each index by referring to the refinement range grade of each index in the tunnel large-deformation susceptibility evaluation table by using the maximum evaluation value of each index; obtaining a total evaluation value of the large deformation susceptibility according to the susceptibility evaluation values of the indexes; and dividing the proneness grade according to the total value of the large-deformation proneness evaluation, corresponding to the accident occurrence probability grade division standards one by one to obtain a large-deformation proneness probability grade, and taking the central value of the corresponding probability value, wherein the central value of the corresponding probability is the large-deformation risk proneness degree.

Further, in the evaluation of the risk of high ground temperature, rock burst and large deformation, the risk degree D is 1.

Further, the economic loss evaluation of the high ground temperature adopts a reference method or an analog estimation method to calculate the special construction added cost of the high ground temperature tunnel; the reference method is to calculate the investment cost of project engineering according to the quota consumption of similar industries and the industry quota pricing criterion of machinery, manpower and materials; the analogy estimation method calculates the investment cost of project engineering according to the investment cost general profiles of similar projects in the past by considering the industry price fluctuation conditions of machinery, manpower and materials; the investment cost per linear meter is obtained, namely the economic loss value per linear meter.

Further, the economic loss evaluation of the rock burst and the large deformation adopts an analog estimation method to calculate the loss cost of the railway tunnel caused by the occurrence of the rock burst and the large deformation disaster; the analogy estimation method calculates the investment cost of project engineering according to the investment cost general profiles of similar projects in the past by considering the industry price fluctuation conditions of machinery, manpower and materials; the investment cost per linear meter is obtained, namely the economic loss value per linear meter. And the economic loss evaluation of the rock burst and the large deformation is obtained through budget.

The invention has the following advantages and beneficial effects:

1. according to the method, a rock burst and large deformation susceptibility evaluation index system of a research area is constructed by screening key influence factors of 3 types of disasters including high ground temperature, rock burst and large deformation; establishing a high ground temperature, rockburst and large deformation susceptibility evaluation model by adopting an Analytic Hierarchy Process (AHP); comprehensively considering the influence of various underground disasters on railway engineering; the method comprises the following steps of establishing a grading system of various disaster types according to the weight of each disaster type inducing factor and determining the grading system by adopting an expert grading method; judging the danger of the railway route selection and the characteristics of underground geological disasters; comprehensively researching the market and the construction site, and determining the unit economic loss of railway engineering caused by the disaster happening under each region; and finally, comprehensively considering the influence of high ground temperature, rock burst and large deformation on railway line engineering, and adopting a comprehensive risk measurement method to construct a railway route selection economic loss evaluation system based on comprehensive risk evaluation of underground geological disasters in the severe mountainous area in southwest of China. The method solves the problems that the railway route selection can not comprehensively analyze and evaluate uncertain factors such as environment, economy and the like, a unified risk assessment method and a route selection theory aiming at multi-source underground geological disasters are lacked, and risk factors and risk events in railway engineering construction are various and difficult to accurately judge.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:

FIG. 1 is a model diagram of risk assessment of an underground geological disaster according to the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.

Example 1:

as shown in fig. 1, the present embodiment provides a railway route selection method based on risk evaluation of a typical underground geological disaster, including the following steps:

Wherein j is 1,2, …, m, m is N^*。

In order to realize uniformity and superposition of the evaluation result of the underground geological disaster, a uniform evaluation model is adopted to carry out risk evaluation on the underground geological disaster along the line scheme; in order to comprehensively consider the economic loss of the railway caused by the disaster, the evaluation result is expressed by an economic value.

Evaluation of susceptibility: due to the fact that geological disaster parameters which can be obtained in the line selection stage are simple, accurate quantitative calculation cannot be conducted, and the improved evaluation method based on the AHP is a semi-quantitative evaluation method combining quantification and qualitative evaluation and is selected for the susceptibility evaluation. The probability of occurrence refers to the probability of occurrence of a geological disaster, and the probability of occurrence of a geological disaster is represented by the probability of occurrence H. And analyzing the influence degree of the factors influencing the disaster occurrence probability on the disaster occurrence probability by adopting an AHP method for evaluating the proneness, and constructing a judgment matrix so as to obtain the action weight of each influence factor on the geological disaster occurrence probability. And then, establishing an susceptibility evaluation system according to the action weight, corresponding the basic data of the disaster section to the evaluation system to obtain an susceptibility evaluation value, and corresponding the evaluation grade to a probability grade specified by a standard so as to obtain a disaster section susceptibility H.

Risk assessment: and (3) threatening the construction possibility of the tunnel after the underground geological disaster occurs, and representing the probability of threatening the construction when the underground geological disaster occurs by using the danger degree D. At present, geological conditions along railway engineering lines under construction and to-be-constructed in the southwest mountainous area of China are complex, the tectonic movement is strong, the routing mainly takes tunnel crossing, part of tunnels are ultra-deep buried long tunnels, the initial stress value of rock mass is high, the risk of high ground stress hard rock burst and high ground stress soft rock large deformation is high, the risk of high ground temperature in a geothermal abnormal area is also high, and once disasters such as high ground temperature, rock burst and large deformation occur, the railway tunnel engineering is damaged, so that D is 1.

And (3) evaluating the length of the disaster section: refers to evaluating the length of a line on which the same type of underground geological disaster occurred.

The following description of the operation of the example is made by evaluation of risk of a single type of underground geological disaster.

Firstly, a high-ground-temperature risk evaluation model:

the evaluation index of high ground temperature risk considers the inducing factors of the high ground temperature thermal damage of the tunnel from the two aspects of heat source and heat transfer in the railway route selection stage, namely 4 key disaster-causing factors of the temperature of a hot (warm) spring, the burial depth, the distance between the hot (warm) spring and a line and the distance between the line and a fault.

The influence of the temperature of the hot (warm) spring, the distance between the hot (warm) spring and a line and the distance between the line and a fault on the high ground temperature of the tunnel is mainly considered as that the hot water transfers heat into the tunnel through fracture structures such as the fault, joints, cracks and the like in deep circulation to cause the high ground temperature heat damage of the tunnel; the buried depth is mainly considered that the formation temperature is increased according to a certain ground temperature gradient along with the increase of the buried depth generally below a local normal temperature zone, namely the buried depth is in direct proportion to the ground temperature.

Evaluating the risk susceptibility of high ground temperature:

(1) determining weight of each index by analytic hierarchy process

Based on the high-ground-temperature risk assessment index system constructed above, a 1-9 scale method (meaning of each scale value is shown in table 1) is adopted, and the importance of each criterion layer relative to a target layer is judged by a pairwise comparison method, so that an A-B judgment matrix is established, and is shown in table 2.

TABLE 1 Scale values table

Scale	Means of
		1	Factor i is as important as factor j
3	Factor i is slightly more important than factor j
		5	Factor i is more important than factor j
7	Factor i is much more important than factor j
		9	Factor i is absolutely more important than factor j
2，4，6，8	Indicating that the importance of the two factors is between the adjacent interpretation scales
		Reciprocal of the	The ratio of the importance of factor j to factor i is a_ij＝1/a_ij

TABLE 2A-B decision matrix

The weight of each scheme is calculated by adopting a maximum characteristic value method, and the A-B judgment matrix is reasonably constructed after the weight is acceptable through consistency test. The calculation results are shown in table 2, where the thermal (hot) spring temperature weight is 0.296, the heat source and linear position distance weight is 0.159, the fault and linear position distance weight is 0.130, and the tunnel buried depth weight is 0.415.

Therefore, the tunnel buried depth and the hot (hot) spring temperature which can be obtained are main risk factors for inducing the high ground temperature thermal damage of the tunnel, and the tunnel which is close to a heat source and a fault is more easily induced to have the high ground temperature phenomenon of the tunnel.

(2) Evaluation rules of expert scoring method

The evaluation system of the high ground temperature susceptibility of the tunnel is shown in Table 3, the maximum evaluation value of each index is obtained by multiplying the corresponding weight by 100 and comprehensively determining according to the opinions of the industry experts; the level evaluation value of the refinement range of each index is determined according to the opinion of an expert in the industry.

TABLE 3 evaluation system for high ground temperature risk of tunnel

(3) Hair-predisposition quantification

According to the system for evaluating the proneness to occurrence, the proneness to occurrence evaluation value of the underground geological disaster section can be obtained by evaluating the proneness to occurrence of the underground geological disaster section, in order to quantify the proneness to occurrence, proneness to occurrence probability grades are obtained according to probability grade standards (table 4) given in the railway tunnel risk evaluation and management provisional regulations, namely the proneness to occurrence grade grades are obtained, and the probability value is taken as a central value and is shown in table 5.

TABLE 4 probability rating criteria

Range of probability	Center value	Description of probability classes	Probability level
				＞0.3	1	Is likely to be	5
0.03～0.3	0.1	Can make it possible to	4
				0.003～0.03	0.01	By chance	3
0.0003～0.003	0.001	It is impossible to use	2
				＜0.0003	0.0001	Is very unlikely to	1

TABLE 5 evaluation value Range of high ground temperature susceptibility

Risk evaluation:

in the evaluation work of the high geothermal susceptibility of the railway tunnel, the high geothermal susceptibility of the tunnel is evaluated aiming at the geothermal abnormal area of the research section, and engineering experience shows that the high geothermal of the tunnel mostly occurs in the geothermal abnormal area; the tunnel high ground temperature is different from other ground geological disasters, such as landslide, debris flow, collapse and the like, such ground geological disasters must occur, and a disaster body moves onto a railway line to damage the railway engineering, namely the ground geological disasters need to perform risk evaluation on whether the disaster body can reach the railway line, namely risk evaluation, and once the tunnel high ground temperature occurs, the tunnel high ground temperature inevitably causes loss to the railway engineering, such as loss caused by reduction of working efficiency of workers, adoption of cooling measures, lining by using heat-resistant materials and the like; in summary, the damage characteristic of the high ground temperature of the tunnel is described, so the danger degree D of the high ground temperature of the tunnel in the geothermal abnormal region in this study is 1, that is, once the high ground temperature of the tunnel occurs, the tunnel engineering is inevitably lost.

Evaluation of economic loss

When a high ground temperature disaster occurs in the tunnel, the working efficiency of workers can be reduced, and the accident rate is increased, so that the construction period and the engineering investment are increased; the concrete can be cracked, so that a heat-resistant material is needed under certain conditions, thereby increasing the engineering investment and not ensuring the engineering quality better; the failure rate of the mechanical equipment is increased, and the construction period delay (indirect loss) and the repair cost (direct loss) of the mechanical equipment are caused; increased engineering costs due to cooling measures; other links increase engineering investment due to high ground temperature of the tunnel. Solving the above problems will necessarily increase the engineering cost.

(1) Increasing cost in special construction of railway high ground temperature tunnel

At present, in China, standards or specifications of special construction cost increasing specifications of railway high-ground-temperature tunnels are not available, but in the industry, the special construction cost increasing specifications of the railway high-ground-temperature tunnels are generally estimated approximately by adopting a reference method or an analog estimation method so as to avoid missing the special construction cost increasing specifications.

1) Reference method: the investment cost of project engineering is estimated according to the rated consumption of similar industries (such as mines, roads, hydropower and the like) and the industry rated pricing criterion of machinery, manpower and materials.

2) The analogy estimation method comprises the following steps: the investment cost of project engineering is estimated by considering the industry price fluctuation conditions of machinery, manpower, materials and the like according to the investment cost profile of similar engineering in the past.

In a Qingyun mountain tunnel to a Pu railway operated by a passing train, a high ground temperature phenomenon occurs, engineering cost indexes of different surrounding rock levels are sorted out according to actual cost data, and the actual comprehensive cost is 2356 yuan/linear meter through calculation and summary. The ginger MAN (2015) refers to the domestic cost standard of the industry similar to the railway tunnel engineering, the application range of the 'consumption quota of coal construction roadway engineering' is closer to that of the railway high-geothermal tunnel engineering, the special construction engineering cost of the railway high-geothermal tunnel is estimated by using a reference method and an analog estimation method according to the standard, and the estimation result is shown in Table 6.

TABLE 6 estimated cost per linear meter of high-ground-temperature tunnel

	Reference method	Analogy estimation method
			Cost (Yuan/Yan rice)	2568	2732
Error (%)	9	16

Considering that most tunnels of western railways crossing the geothermal abnormal area in China are in high-altitude areas and construction difficulty is high, 2732 yuan/linear meter which is high in cost is adopted for calculating risk loss of the high-geothermal tunnels of the railways in the research, and the estimation precision of the analog estimation algorithm result can meet the requirement of compiling investment pre-estimation in the line selection stage.

(2) Special construction increasing cost for railway high-ground-temperature tunnel construction in plateau area

The "road engineering capital construction project approximate calculation budgeting method" defines plateau construction as construction in an area with an altitude of more than 1500m (ministry of transportation of the people's republic of china, 2007), and this study is referred to this regulation. The cost increase of the railway high-ground-temperature tunnel construction in the plateau area refers to the extra cost which is required to be increased for completing the same workload because the workload which can be completed by one working day or one shift in a non-plateau area cannot be completed in the plateau area (above the elevation of 1500 m) due to the influence of adverse factors such as the climate, the air pressure and the like in the area with the elevation of 1500 m. The plateau construction increasing rate is proposed by referring to Wanggui Ling (2012) for special construction increasing rate of railway high-ground-temperature tunnels in plateau regions, and is shown in table 7, and the calculation formula is as follows.

V＝V₀*r₁

In the formula: v is the cost for increasing the rate in consideration of the construction of the plateau railway engineering, and is unit/linear meter;

V₀the railway construction cost of the non-plateau area is 2732 yuan/linear meter;

r₁increasing the rate for the construction of the plateau railway engineering.

TABLE 7 elevated tariff for railway engineering plateau construction

Note: altitude less than 2000_mThe plateau construction increasing rate is not considered.

(3) Risk economic loss considering high ground temperature risk probability

After the high ground temperature susceptibility of a certain section of the railway tunnel is evaluated, the high ground temperature risk loss of the evaluation section can be obtained by multiplying the susceptibility, the risk degree, the evaluation section length and 4 loss values per linear meter according to the following formula.

R＝H·D·B·V

In the formula: h is the probability of high ground temperature occurrence;

d is danger of high ground temperature, 1 is taken;

b is the length of the high ground temperature generating segment;

loss per linear meter of the high ground temperature section of V.

Rock burst risk evaluation

Rock burst risk evaluation index

Rockburst is a dynamic unstable underground geological disaster (lietianbin et al, 2016) in which the phenomena of burst loosening, peeling, catapulting and even throwing are caused by the fact that hard and brittle surrounding rocks have different tunnel wall stress due to excavation unloading under the condition of relatively high ground stress in the excavation process of underground engineering, and elastic strain energy stored in rock masses is suddenly released.

The rock burst is related to lithology and rock mass structure, and generally occurs in rock mass with hard rock quality, good structural integrity, low fresh or weathering degree, low development degree of weak structural surfaces such as fracture joints and the like and good brittleness; rock burst is related to buried depth and ground stress, the buried depth is generally in direct proportion to the ground stress, and rock mass is more prone to rock burst or the influence degree of rock burst is higher in a high ground stress area; rock burst is related to structure, and rock burst is more likely to occur or the influence degree of rock burst is higher in stress concentration areas such as a fold core part and an extrusion belt; the rock burst is related to underground water, the rock burst usually occurs in dry rock mass, the underground water can soften the rock mass, the strength of the rock mass is reduced, and the reserved elastic energy is not enough to generate the rock burst; the rock burst is related to time, and generally lags behind the excavation of the face, namely the rock burst does not occur for hours or even days or months after the excavation of the face; the rock burst is related to the shape of the section, and the essence of the rock burst is that the shape of the tunnel excavation section is irregular, so that the local stress of the excavation section is concentrated, and the rock burst is easier to occur in a stress concentration area; rockburst is also related to excavation, support, and timing of support (sun xuanning, etc., 2012).

Considering the easy acquireability of risk evaluation calculation data in the railway route selection stage, only considering the influence of geological factors on rock burst, and finally selecting 4 key disaster-causing factors of rock strength, ground stress, geological structure and surrounding rock level by analyzing key influence factors of rock burst and expert opinions of the industry.

Evaluation of Hair-growing ability

(1) Determining weight of each index by analytic hierarchy process

Based on the rock burst risk assessment index system constructed above, a 1-9 scale method (meaning of each scale value is shown in table 1) is adopted, and importance of each criterion layer relative to a target layer is judged through a pairwise comparison method, so that an A-B judgment matrix is established, and the A-B judgment matrix is shown in table 8.

TABLE 8A-B decision matrix

The weights of all the criteria of the standard layer are calculated by adopting a maximum characteristic value method, the weights are acceptable through consistency test, an A-B judgment matrix is reasonably constructed, and the calculation result is shown in Table 8. And calculating to obtain lithology condition weight of 0.384, ground stress condition weight of 0.300, geological structure condition weight of 0.126 and surrounding rock condition weight of 0.190. Because each criterion layer only corresponds to one sub-criterion, the weight ratio of each sub-criterion is consistent with the weight ratio of the corresponding criterion, namely the rock strength weight is 0.384, the ground stress weight is 0.300, the geological structure weight is 0.126, and the surrounding rock grade weight is 0.190, so that the obtained higher rock strength and higher ground stress are main risk factors for inducing rock burst, and meanwhile, the better geological structure condition and surrounding rock condition have certain catalytic action on the occurrence of rock burst.

(2) Evaluation rules of expert scoring method

The evaluation system of tunnel rockburst susceptibility is shown in table 9, wherein the maximum evaluation value of each risk evaluation index is determined by multiplying the weight by 100 and combining the opinions of the industry experts, and the level score of the refinement range of each index is determined according to the opinions of the industry experts.

TABLE 9 evaluation system for tunnel rockburst explosiveness

(3) Hair-predisposition quantification

According to the system for evaluating the proneness to occurrence, the proneness to occurrence evaluation value of the geological disaster section can be evaluated so as to obtain the evaluation value of the proneness to occurrence of the disaster section, in order to quantify the proneness to occurrence, proneness probability grades are obtained according to probability grade standards (table 4) given in the provisions of railway tunnel risk evaluation and management temporary, namely the proneness probability grades are divided, and the probability value is taken as a central value and is shown in a table 10.

TABLE 10 evaluation value Range of rockburst susceptibility

Risk assessment

At present, geological conditions along railway engineering lines under construction and to-be-constructed in southwest mountainous areas in China are complex, the tectonic movement is strong, the routing mainly comprises tunnel crossing, part of tunnels are ultra-deep buried long tunnels, the tunnels are mostly in a high ground stress state, and engineering experience shows that rock burst is more likely to occur in hard rock tunnels in the high ground stress areas; the high ground stress hard rock burst disaster is different from other ground geological disasters, such as landslide, debris flow, collapse and the like, the ground geological disasters need to occur and damage railway engineering only when a disaster body moves onto a railway line, namely the ground geological disasters need to perform risk evaluation on whether the disaster body can reach the railway line, namely risk evaluation, and once the rock burst disaster occurs, the rock burst disaster inevitably causes loss to the railway engineering, such as direct and indirect loss of support damage, personal casualties, construction period delay and the like; in summary, the damage characteristic of the tunnel rockburst is considered, so that the risk degree D of the high-ground-stress hard rock rockburst in the research is 1, that is, once the high-ground-stress hard rock rockburst occurs, the loss of the tunnel engineering is inevitably caused.

Evaluation of economic loss

Since the period of the research object is the railway line selection stage, 3 assumptions are provided for the risk economic loss calculation of rock burst: (1) assuming that the rock burst sections of the tunnel are all supported conventionally; (2) corresponding support measures corresponding to rock burst disaster grades are adopted in tunnel rock burst sections;

(1) suppose 1 rockburst economic loss

1) Direct economic loss

Assuming that the rock burst section of the tunnel is supported by a conventional support, the direct economic loss refers to the loss cost increased by re-supporting the surrounding rock after the damage of the primary support caused by the rock burst disaster such as the damage of concrete, a reinforcing mesh, a steel arch, an anchor rod and the like in the primary support and the damage of the primary support caused by the rock burst, namely the direct economic loss of the rock burst comprises the damage cost of the primary support and the cost required by re-supporting. However, in consideration of the risk loss, the cost of the re-shoring material is not considered here, so the primary cost only comprises the cost of the conventional primary material and the cost of personnel and equipment, but due to the rock burst loss caused by the wrong shoring means, the time loss of re-shoring is caused, and due to the fact, the loss caused by the time consumption of re-shoring needs to be considered in the indirect economic loss. And calculating the project consumption per linear meter of the tunnel body (table 11) by referring to the rock burst supporting structure in the railway tunnel construction, and obtaining the direct economic loss caused by the rock burst of each grade according to the project construction cost table (table 12).

TABLE 11 engineering quantities per linear meter of hole body

Note: phi 22 is a system mortar anchor rod; phi 40 is a seam tube type anchor rod

TABLE 12 Tunnel engineering construction cost table

Wherein the damage cost X of the conventional primary support material is shown as the formula

The equipment cost Y of the conventional primary support personnel is as the formula

Y＝5t；

The direct economic loss value Z is expressed by the formula:

Z＝X+Y，

in the formula, Z is direct economic loss under conventional support;

h_i: the concrete consumption h under the conventional support₁The amount of the reinforcing mesh is h₂Steel arch frame dosage h₃Dosage of anchor rod h₄；

k_i: concrete unit price k under conventional support₁Steel bar net unit price k₂Steel arch frame unit price k₃Anchor unit price k₄；

t: the time consumed by each meter of the tunnel support is researched, the tunnel construction is delayed by one day and lost by about 5 ten thousand yuan, and the cost converted from the time consumed by the support is calculated according to one day of 5 ten thousand yuan (including personnel and equipment cost).

The conventional supporting time consumption was estimated by the PERT method described above, and the supporting time consumption per linear meter of the tunnel was taken as a measure, as shown in Table 13.

TABLE 13 conventional preliminary bracing time consumption estimation distribution parameter table

Note: the time units in the table are days.

As can be seen from tables 11 and 12, the conventional timbering initial material loss cost is:

x is 3117.58 (yuan/long rice)

From table 13, the equipment costs for the conventional support personnel are:

the direct economic loss Z under conventional support was thus calculated to be 11450.91 yuan/linear meter.

2) Indirect economic loss

The indirect economic loss is the loss caused by the rock burst disaster, and comprises the expenses of mechanical equipment use, labor cost, water and electricity cost and the like which are still generated continuously. The construction period delay caused by the rock burst disaster mainly comprises the shutdown and completion time t of the engineering construction project₁And re-support elapsed time t₂Through investigation of similar projects, the delay loss of the construction period caused by rock burst is about 5 ten thousand yuan/day, and the expected delay loss value of the construction period caused by each rock burst grade is counted in the table 14. The delay loss of the construction period is calculated as the formula

W＝5(t₁+t₂)；

In actual calculation, comprehensively considering all aspects, and adopting an average value t of the sum of the downtime and the mortgage time of the engineering project and the retesting time₃Performing calculation as formula

In the formula: w_j: j is I, I; respectively representing the indirect economic losses of a slight rock burst, a medium rock burst and a strong rock burst.

TABLE 14 expected delay loss for a project due to various rock burst classes

Grade of rockburst	Slight rock burst	Moderate rockburst	Strong rock burst
				Days of shutdown (d)	0～2	2～4	4～10
Re-support time (d)	0～1	1～2	2～5
				Calculating the adopted time (d)	0.75	2.25	5.25

Note: the time units in the table are days.

The indirect economic losses of slight rock burst, medium rock burst and strong rock burst are obtained through calculation:

W_Ⅰ37500 (yuan/long rice)

W_ⅡBecoming 112500 (yuan/long rice)

W_ⅢBecoming 262500 (yuan/long rice)

3) Total economic loss of rock burst

The average risk economic loss per linear meter of the rockburst is the sum of the direct economic loss and the indirect average risk economic loss, and the formula is shown as follows.

In the formula: v_pAverage risk economic loss per linear meter for slight, moderate, and strong rockburst;

z is the direct economic loss under the conventional support;

W_j: j is I, I; respectively representing indirect economic losses caused by slight rock burst, medium rock burst and strong rock burst;

comprehensively considering all factors, adopting rock burst average economic loss V_pAnd (3) carrying out substitution calculation:

(2) suppose 2 rock burst economic losses

And (3) supposing that corresponding support measures corresponding to rock burst disaster grades are adopted in the rock burst section of the tunnel, the economic loss is the difference between the cost of each support grade and the cost of the conventional support, and the cost indirectly generated by the time consumed by adopting the corresponding support grade of the rock burst compared with the conventional support is considered, and the daily loss is calculated according to the loss of 5 ten thousand yuan.

In actual engineering, the shoring time is considered as a random variable due to the influence of various sudden factors. The calculated values are shown in table 15, which are expressed by a triangular distribution, converted into an equivalent normal distribution, and calculated by estimating the engineering measurement of each level of preliminary bracing in each linear meter of the tunnel, and taking the mean value as the calculated value.

TABLE 15 distribution parameter table for estimation of preliminary bracing time consumption

Note: the time units in the table are days.

2) Economic loss calculation

The economic loss in case 2 is assumed to be calculated as an average of the slight rock burst, the medium rock burst and the strong rock burst, with reference to the engineering material usage and the material construction cost of tables 11 and 12, as shown in table 16.

TABLE 16 economic loss calculation Table

(4) Actual calculation of economic loss of rock burst

1) Plain area

Comprehensively considering the actual situation, when the economic loss of the rockburst section of the selective route is calculated, the conventional support is adopted according to 20% of rockburst sections (namely 20% of rockburst sections are calculated according to the hypothesis 1), the corresponding support measures corresponding to the rockburst disaster grade are adopted in 80% of rockburst sections (namely 80% of rockburst sections are calculated according to the hypothesis 2), and finally V loss per linear meter is realized₀Is 47813.29 yuan/linear meter.

V₀47813.29 (yuan/linear meter) is 148950.91 × 0.2+22528.89 × 0.8 ═ 47813.29

2) Incremental engineering cost calculation in plateau regions

The "road engineering capital construction project approximate calculation budgeting method" defines plateau construction as construction in an area with an altitude of more than 1500m (ministry of transportation of the people's republic of china, 2007), and this study is referred to this regulation. The cost increase of the railway high-ground-temperature tunnel construction in the plateau area refers to the extra cost which is required to be increased for completing the same workload because the workload which can be completed by one working day or one shift in a non-plateau area cannot be completed in the plateau area (above the elevation of 1500 m) due to the influence of adverse factors such as the climate, the air pressure and the like in the area with the elevation of 1500 m. The special construction increasing rate of the railway high-ground-temperature tunnel construction in the plateau region is provided with reference to Wangui linger (2012), and the plateau construction increasing rate is provided with a calculation formula as follows.

V＝V₀*r₁

V₀the railway construction cost of the non-plateau area is 47813.29 yuan/linear meter;

3) Loss of risk

And after calculating the economic loss of rock burst of each linear meter of the tunnel, referring to a railway tunnel risk assessment and management provisional regulation accident occurrence probability grade table. And calculating the economic loss of the tunnel rock burst risk corresponding to the rock burst disaster occurrence probability, namely calculating plateau loss and multiplying the plateau loss by the disaster occurrence probability to obtain the final risk loss, wherein the calculation formula is as follows.

R＝H·D·B·V

In the formula: h is the probability of occurrence of rock burst;

d is danger of rock burst, and 1 is taken;

b is the length of the rock burst generation section;

loss per linear meter of V-rockburst.

Three, large deformation risk evaluation

Large deformation risk evaluation index

The large deformation of the tunnel surrounding rock is the surrounding rock composed of weak rock masses, under the action of underground water, high ground stress or self expansibility, the self-bearing capacity of the tunnel surrounding rock is partially or completely lost, the deformation of the tunnel surrounding rock is restrained without effective restraint, so that the plastic deformation of the tunnel surrounding rock is damaged, and the surrounding rock support is damaged to different degrees (more than the design reserved deformation), and the damage characteristic of the large deformation of the tunnel surrounding rock is the progressive and time effect of the deformation (Litianbin and the like, 2016).

The main influencing factors of the large deformation of the tunnel surrounding rock can be summarized as the surrounding rock conditions, the lithological conditions and the ground stress conditions.

In terms of surrounding rock conditions, the more broken the rock mass structure, the more underground water, the higher the surrounding rock level, and the worse the surrounding rock quality, the higher the probability of large deformation; in terms of lithological conditions, the lower the uniaxial compressive strength and the lower the elastic modulus of the rock and the higher the expansibility of the rock, the higher the probability of large deformation of the rock; in terms of ground stress conditions, the greater the initial ground stress value of a rock mass, the greater the probability of its large deformation (menlando et al, 2010); the large deformation of the tunnel surrounding rock is related to design factors, such as untimely dynamic design, tunnel section size and the like; the large deformation of the tunnel surrounding rock is also related to construction factors, such as excavation schemes, unreasonable support measures, untimely support and the like.

A railway route selection stage, wherein only the influence of geological factors on large deformation is considered; meanwhile, 4 key disaster-causing factors of rock strength, ground stress, geological structure and surrounding rock level are selected after the risk evaluation calculation data are discussed with industry experts in consideration of the easiness in obtaining of risk evaluation calculation data in the early line selection stage.

Evaluation of Hair-growing ability

(1) Determining weight of each index by analytic hierarchy process

Based on the rock burst risk assessment index system constructed above, a 1-9 scale method (meaning of each scale value is shown in table 1) is adopted, and importance of each criterion layer relative to a target layer is judged through a pairwise comparison method, so that an A-B judgment matrix is established, and the A-B judgment matrix is shown in table 17.

TABLE 17A-B decision matrix

The weights of all the criteria of the standard layer are calculated by adopting a maximum characteristic value method, the weights are acceptable through consistency test, an A-B judgment matrix is reasonably constructed, and the calculation result is shown in a table 17. And calculating to obtain lithology condition weight of 0.362, ground stress condition weight of 0.280, geological structure condition weight of 0.120 and surrounding rock condition weight of 0.238. Because each criterion layer only corresponds to one sub-criterion, the weight ratio of each sub-criterion is consistent with the weight ratio of the corresponding criterion, namely the rock strength weight is 0.362, the ground stress weight is 0.280, the geological structure weight is 0.120 and the surrounding rock grade weight is 0.238, so that the lower rock strength and the higher ground stress are main risk factors for inducing large deformation of the surrounding rock, and meanwhile, the poorer geological structure condition and the surrounding rock condition have certain catalytic action on the large deformation of the surrounding rock.

(2) Evaluation rules of expert scoring method

The tunnel large deformation susceptibility evaluation index system and the evaluation values are shown in table 18, wherein the maximum evaluation value of each risk evaluation index is determined by multiplying the weight by 100 and combining the opinions of the industry experts, and the level score of the refinement range of each index is determined according to the opinions of the industry experts.

TABLE 18 evaluation system for large deformation and easiness in occurrence of tunnel

(3) Hair-predisposition quantification

According to the susceptibility evaluation system, the susceptibility evaluation can be carried out on the geological disaster points so as to obtain the susceptibility evaluation value of the disaster points, in order to quantify the susceptibility, susceptibility probability grades are correspondingly obtained according to probability grade standards (table 4) given in the provisions of railway tunnel risk evaluation and management temporary regulations, namely the susceptibility grades are graded, and the probability value is taken as the central value and is shown in table 19.

TABLE 19 evaluation value Range of susceptibility to Large deformation

Risk assessment

At present, geological conditions along railway engineering lines under construction and to-be-constructed in southwest mountainous areas in China are complex, the tectonic movement is strong, the routing mainly takes tunnel crossing, part of tunnels are ultra-deep buried long tunnels, the tunnels are mostly in a high ground stress state, and engineering experience shows that large deformation of surrounding rocks is more likely to occur in soft rock tunnels in the high ground stress areas; the high ground stress soft rock large deformation disaster is different from other ground geological disasters, such as landslide, debris flow, collapse and the like, the ground geological disasters need to occur and damage railway engineering only when a disaster body moves onto a railway line, namely the ground geological disasters need to perform risk evaluation on whether the disaster body can reach the railway line, namely risk evaluation, and once the surrounding rock large deformation disaster occurs, the surrounding rock large deformation disaster can cause damage to the railway engineering, such as direct and indirect damage of support damage, casualties, construction period delay and the like; to sum up the disaster characteristics of large deformation of tunnel surrounding rocks, the danger degree D of large deformation of high ground stress soft rocks in the research is 1, namely, once the large deformation of the high ground stress soft rocks occurs, the large deformation of the high ground stress soft rocks inevitably causes loss to tunnel engineering.

Evaluation of economic loss

Since it is in the railway line selection stage, 3 assumptions are proposed for the risk economic loss calculation of large deformation: (1) assuming that the large deformation section of the tunnel is supported by a conventional support; (2) assuming that corresponding support measures corresponding to the grade of the large deformation disaster are adopted in the large deformation section of the tunnel; (3) assuming that 20% of large deformation sections adopt conventional support, and 80% of large deformation sections adopt corresponding support measures corresponding to the grade of the rock burst disaster;

(1) assumption of 1 large deformation economic loss

1) Direct economic loss

Assuming that the large deformation section of the tunnel is supported by a conventional support, the direct economic loss refers to the cost required for re-supporting the surrounding rock after the damage to concrete, a reinforcing mesh, a steel arch, an anchor rod, a small grouting guide pipe and the like in the primary support and the large deformation of the surrounding rock are caused by the large deformation disaster, and the later expansion excavation. The direct economic loss is mainly the cost of primary damage loss, the cost of re-support increase and the cost of later-stage expanding excavation. However, considering the risk loss, the re-shoring cost and the post-excavation cost are not considered here, so the primary shoring cost only comprises the conventional primary shoring material cost and the personnel and equipment cost, but the loss of time for re-shoring is caused due to the large deformation loss caused by the wrong shoring means, and the loss caused by the time for re-shoring needs to be considered in the indirect economic loss due to the fact that the loss is caused. The construction amount (table 20) of each linear meter of the tunnel body is calculated by referring to the large deformation supporting structure for railway tunnel construction, and then the direct economic loss caused by each large deformation grade is obtained according to the construction cost table (table 21).

TABLE 20 engineering dosage per linear meter of hole body

Meter 21 construction cost meter for tunnel engineering

Wherein the damage cost X of the conventional primary support material is as the formula

Y＝5t、

Direct economic loss value Z is as in equation 17:

Z＝X+Y

in the formula, Z is direct economic loss under conventional support;

h_i: the concrete consumption h under the conventional support₁The amount of the reinforcing mesh is h₂Steel arch frame dosage h₃Dosage of anchor rod h₄The dosage of the small conduit for grouting h₅；

k_i: concrete unit price k under conventional support₁Steel bar net unit price k₂Steel arch frame unit price k₃Anchor unit price k₄Grouting small conduit unit price k₅；

t: the time consumed by each meter of the tunnel support is researched, the tunnel construction is delayed by about 5 ten thousand yuan per day, and the cost converted from the time consumed by the support is calculated according to 5 ten thousand yuan per day.

The conventional supporting time consumption was estimated by the PERT method described above, and the supporting time consumption per linear meter of the tunnel was taken as a measure, as shown in Table 22.

TABLE 22 conventional preliminary bracing time consumption estimation distribution parameter table

Note: the time units in the table are days.

As can be seen from tables 20 and 21, the conventional timbering initial material loss cost is:

x is 9359.42 (yuan/long rice)

From table 22, the equipment costs for the conventional support personnel are:

the direct economic loss Z under the conventional support is obtained by calculation and is 19776.09 yuan/linear meter.

2) Indirect economic loss

The indirect economic loss is the loss caused by the large deformation disaster of the surrounding rock, which causes the delay of the construction period, and comprises the expenses of mechanical equipment, labor, water and electricity, and the like, which are still generated continuously. The construction period delay loss caused by the surrounding rock large deformation disaster mainly comprises the shutdown and completion time t of the engineering construction project₁And the time t taken for re-support₂Through investigation of similar projects, the construction period delay loss caused by rock burst is about 5 ten thousand yuan/day, and the expected value of the construction period delay loss caused by large deformation levels of surrounding rocks is counted in the table 23. The delay loss of the construction period is calculated as the formula

W＝5(t₁+t₂)；

In the formula: w_j: j is I, I; each represents an indirect economic loss of slightly large deformation, moderately large deformation and strongly large deformation.

TABLE 23 expected values for construction time delay loss due to large deformation levels

Large deformation class	Slight large deformation	Moderate to large deformation	Strong large deformation
				Days of shutdown (d)	0～2	2～4	4～10
Re-support time (d)	0～1	1～2	2～5
				Calculating the adopted time (d)	0.75	2.25	5.25

Note: the time units in the table are days.

The indirect economic losses of slight large deformation, medium large deformation and strong large deformation are obtained through calculation:

W_Ⅰ37500 (yuan/long rice)

W_ⅡBecoming 112500 (yuan/long rice)

W_ⅢBecoming 262500 (yuan/long rice)

3) Gross economic loss with large deformation risk

The average risk economic loss per linear meter of the large deformation of the surrounding rock is the sum of the direct economic loss and the indirect average risk economic loss, and the formula is as follows

In the formula: v_pAverage risk economic loss per linear meter for slight large deformation, medium large deformation and strong rock large deformation;

z is the direct economic loss under the conventional support;

W_j: j is I, I; each represents indirect economic losses due to slight large deformation, moderate large deformation and intense large deformation;

comprehensively considering all factors, adopting large deformation average economic loss V_pAnd (3) carrying out substitution calculation:

(2) assumption 2 large deformation economic loss

Assuming that corresponding support measures corresponding to large deformation disaster grades are adopted in large deformation sections of the tunnel, the economic loss is the difference between the cost of each support grade and the cost of conventional support, and the cost indirectly generated by the time consumed by adopting the large deformation corresponding support grade to be more than that of the conventional support is considered, and the cost is still calculated according to the loss of 5 ten thousand yuan per day.

1) Preliminary bracing time consumption estimation

In actual engineering, the shoring time is regarded as a random variable because of unavoidable influence of various sudden factors. The results are described by triangular distribution, and converted into equivalent normal distribution, and the mean value is taken as a calculation value, and the unit is each linear meter of the tunnel, and the engineering measurement of the preliminary bracing of each grade is estimated, as shown in table 24.

Table 24 initial support cost estimation distribution parameter table

Note: the time units in the table are days; the unit of cost is Yuan;

2) economic loss calculation

The calculated economic loss values for the case of assumption 2 are shown in table 25 with reference to the amount of engineering materials and the material cost.

Table 25 assumption 2 economic loss calculation table

(3) Actual calculation of large deformation economic loss

1) Plain area

Comprehensively considering the actual situation, when the economic loss of the large deformation section of the selected route is calculated, the conventional support is adopted according to 20% of the large deformation section (namely 20% of the large deformation section is calculated according to the hypothesis 1), the corresponding support measures corresponding to the large deformation disaster grade are adopted in 80% of the large deformation section (namely 80% of the large deformation section is calculated according to the hypothesis 2), and finally the loss V per linear meter is realized₀Is 51161.27 yuan/linear meter.

V₀51161.27 (yuan/linear meter) is 157276.09 × 0.2+24632.56 × 0.8 ═ 51161.27

2) Incremental engineering cost calculation in plateau regions

The "road engineering capital construction project approximate calculation budgeting method" defines plateau construction as construction in an area with an altitude of more than 1500m (ministry of transportation of the people's republic of china, 2007), and this study is referred to this regulation. The cost increase of the railway high-ground-temperature tunnel construction in the plateau area refers to the extra cost which is required to be increased for completing the same workload because the workload which can be completed by one working day or one shift in a non-plateau area cannot be completed in the plateau area (above the elevation of 1500 m) due to the influence of adverse factors such as the climate, the air pressure and the like in the area with the elevation of 1500 m. The plateau construction increasing rate is proposed by referring to Wanggui Ling (2012) for special construction increasing rate of railway high-ground-temperature tunnel construction in plateau regions, see table 7, and the calculation formula is as shown in the formula

V＝V₀*r₁

V₀the railway construction cost of the non-plateau area is 51161.27 yuan/linear meter;

3) Loss of risk

And after calculating the economic loss of the large deformation of the surrounding rock of each linear meter of the tunnel, referring to a railway tunnel risk assessment and management temporary regulation accident occurrence probability grade table. And calculating the economic loss of the large deformation risk of the tunnel corresponding to the occurrence probability of the large deformation disaster of the surrounding rock, namely calculating the plateau loss and multiplying the plateau loss by the occurrence probability of the disaster to obtain the final risk loss. Formula for calculation such as

R＝H·D·B·V

In the formula: h is the probability of occurrence of large deformation;

d is the danger of large deformation, and 1 is taken;

b is the length of the large deformation generation segment;

loss per linear meter of large V deformation section.

In summary, the following steps: in southwest and severe mountainous areas with complex geological environment, the comprehensive risk assessment work based on typical underground geological disasters (high ground temperature, rock burst and large deformation) is especially important for the railway engineering route selection stage, and research results can be directly applied to actual engineering and can also provide guidance and regulation for route selection design of other similar engineering and revise accumulated information.

The typical underground geological disasters of the area, namely high ground temperature, rock burst and large deformation disasters, are judged by statistically analyzing geological data of railway projects in the southwest mountainous areas of China to be built. Through summarizing similar engineering experience and similar underground geological disaster cases, influence factors of 3 types of underground geological disasters including high ground temperature, rock burst and large deformation are analyzed, key influence factors of 3 types of disasters including high ground temperature, rock burst and large deformation are screened, 4 indexes of temperature of hot (warm) spring, buried depth, distance between the hot (warm) spring and a line and distance between the line and a fault are selected to construct a high ground temperature susceptibility evaluation index system of a research area, and 4 indexes of rock strength, ground stress, geological structure and surrounding rock level are selected to respectively construct a vulnerability evaluation index system of rock burst and large deformation of the research area.

Based on a typical underground geological disaster susceptibility evaluation index system in a severe mountain area in southwest of China, respectively determining the weight of high ground temperature, rockburst and large deformation induction factors by adopting a hierarchical Analysis (AHP) method, respectively constructing a grading system of high ground temperature, rockburst and large deformation by combining an expert grading method, respectively corresponding to accident occurrence grading probability standards one by one, establishing susceptibility grade standards of high ground temperature, rockburst and large deformation, respectively constructing susceptibility evaluation models of high ground temperature, rockburst and large deformation according to the susceptibility grade standards, and respectively calculating the susceptibility of each typical underground geological disaster; the method comprises the steps of respectively defining the risk degrees of high ground temperature, rockburst and large deformation by analyzing the disaster influence characteristics of the high ground temperature, rockburst and large deformation and combining with expert opinions; respectively establishing economic loss calculation models of high ground temperature, rock burst and large deformation by market research, referring to similar engineering experience and predecessor research results; and (3) combining the susceptibility, the risk and the economic loss together by adopting a comprehensive risk measurement method to respectively construct a high ground temperature, rockburst and large deformation risk evaluation model. And finally, comprehensively considering the influence of each single underground geological disaster on the railway engineering, and establishing a comprehensive typical underground geological disaster risk assessment model considering risk expected loss.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A railway route selection method based on typical underground geological disaster risk evaluation is characterized by comprising the following steps: the method comprises the following steps:

s2, determining economic loss V of each linear meter of the railway tunnel engineering caused by the occurrence of a single disaster type disaster, and determining the length B of the disaster section;

Wherein j is 1,2, …, m, m is N^*。

2. The railway line selection method based on typical underground geological disaster risk evaluation as claimed in claim 1, characterized in that: the disaster types include high ground temperature, rock burst, and large deformation.

3. The railway line selection method based on typical underground geological disaster risk evaluation as claimed in claim 2, characterized in that: the method for evaluating the susceptibility in the risk evaluation of the high ground temperature comprises the following steps:

s104, multiplying the corresponding weight of each index by 100 to obtain the maximum evaluation value of each index, and determining the susceptibility evaluation value of each index by adopting the maximum evaluation value of each index to refer to the thinning range grade of each index in the tunnel high ground temperature susceptibility evaluation system table; obtaining a total evaluation value of high ground temperature susceptibility according to the susceptibility evaluation values of the indexes; and dividing the total value according to the high-ground-temperature susceptibility evaluation into susceptibility grades, corresponding to the accident occurrence probability grade division standards one by one to obtain the high-ground-temperature susceptibility probability grade, and taking the central value of the corresponding probability value, wherein the central value of the corresponding probability is the high-ground-temperature susceptibility.

4. The railway line selection method based on typical underground geological disaster risk evaluation as claimed in claim 2, characterized in that: the method for evaluating the susceptibility in the risk evaluation of the rock burst comprises the following steps:

s201, determining rock burst influence factors, and taking the rock burst influence factors as rock burst disaster-causing factors, wherein the rock burst disaster-causing factors comprise lithologic conditions, ground stress conditions, geological structure conditions and surrounding rock conditions; the lithology condition is rock strength, the ground stress condition is a ground stress value, and the surrounding rock condition is a surrounding rock grade;

s204, multiplying the corresponding weight of each index by 100 to obtain the maximum score of each index, and determining the susceptibility evaluation value of each index by referring to the refinement range grade of each index in the tunnel rock burst susceptibility evaluation table by the maximum evaluation value of each index; obtaining a total rock burst risk susceptibility evaluation value according to the susceptibility evaluation values of the indexes; and dividing the rock burst easiness evaluation total value into easiness grades according to the rock burst risk easiness evaluation total value, corresponding to the accident occurrence probability grade division standards one by one to obtain rock burst easiness probability grades, and taking the central value of the corresponding probability value as the rock burst risk easiness evaluation degree.

5. The railway line selection method based on typical underground geological disaster risk evaluation as claimed in claim 2, characterized in that: the susceptibility evaluation method in the risk evaluation of the large deformation comprises the following steps:

s301, determining large deformation influence factors, and taking the large deformation influence factors as large deformation disaster-causing factors, wherein the large deformation disaster-causing factors comprise lithologic conditions, ground stress conditions, geological structure conditions and surrounding rock conditions; the lithology condition is rock strength, the ground stress condition is a ground stress value, and the surrounding rock condition is a surrounding rock grade;

6. The railway line selection method based on typical underground geological disaster risk evaluation as claimed in claim 2, characterized in that: in the risk evaluation of high ground temperature, rock burst and large deformation, the risk degree D is 1.

7. The railway line selection method based on typical underground geological disaster risk evaluation as claimed in claim 2, characterized in that: the economic loss evaluation of the high ground temperature adopts a reference method or an analog estimation method to calculate the special construction added cost of the high ground temperature tunnel; the reference method is to calculate the investment cost of project engineering according to the quota consumption of similar industries and the industry quota pricing criterion of machinery, manpower and materials; the analogy estimation method calculates the investment cost of project engineering according to the investment cost general profiles of similar projects in the past by considering the industry price fluctuation conditions of machinery, manpower and materials; the investment cost per linear meter is obtained, namely the economic loss value per linear meter.

8. The railway route selection method based on the risk evaluation of the typical underground geological disaster as claimed in claim 2, wherein the unit economic loss evaluation of the rockburst and the large deformation adopts an analogy estimation algorithm to calculate the loss cost of the rockburst and the large deformation disaster on the railway tunnel; the analogy estimation method calculates the investment cost of project engineering according to the investment cost general profiles of similar projects in the past by considering the industry price fluctuation conditions of machinery, manpower and materials; the investment cost per linear meter is obtained, namely the economic loss value per linear meter.