WO2022242156A1 - Weathered sandstone-containing metro station foundation pit excavation equipment selection method - Google Patents

Abstract

Disclosed in the present invention is a weathered sandstone-containing metro station foundation pit excavation equipment selection method, comprising the following steps: (1) surveying and determining geological conditions before excavation of a metro station foundation pit, and determining geological stratums contained in the geology; (2) according to a matching relationship between the rock-soil strength and thickness of each geological stratum and excavation equipment, determining the work efficiency assignment of each geological stratum and the excavation equipment; and (3) selecting the excavation equipment of each geological stratum according to the working efficiency assignment. In the present invention, for the weathered sandstone-containing metro station foundation pit, a geological condition and optional equipment configuration table is established before excavation of the foundation pit, various excavation schemes are analyzed, and a scheme having the optimal engineering value is obtained by means of combination, comparison and selection. The method reduces selection errors caused by human limitation, avoids resource waste, and supports safe and efficient engineering construction.

Description

A selection method for excavation equipment of subway station foundation pit containing weathered sandstone technical field

The invention belongs to the field of civil engineering, in particular to a method for selecting excavation equipment for foundation pits of subway stations.

Background technique

Due to geological conditions, surrounding environment, resource allocation and other reasons in the excavation of foundation pits of subway stations, there are many foundation pit excavation equipments, random selection, and lack of scientific evaluation-based scheme selection methods, which often result in waste of resources and affect construction progress and costs. , and even endanger the safety of the foundation pit and the surrounding environment.

Based on the determination of the width and depth of ordinary subway stations, according to the geological conditions found in geological surveys, combined with the performance of existing advanced equipment such as excavation, demolition, shipment, and lifting, as well as past construction data and related experience, a construction scheme feasibility selection system is established , using methods such as analysis, comparison and selection to determine the optimal value for construction is of great significance for the safe, smooth, efficient and low-cost excavation of subway station foundation pits.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the above background technology, and provide a safe, smooth, high-efficiency and low-cost method for selecting excavation equipment for foundation pits of subway stations containing weathered sandstone. In order to solve the problems of the technologies described above, the technical solution proposed by the present invention is:

A method for selecting excavation equipment for a subway station foundation pit containing weathered sandstone, comprising the following steps:

(1) Investigate and determine the geological conditions before the excavation of the foundation pit of the subway station, and determine the geological layers included in the geology;

(2) According to the matching relationship between the rock and soil strength and thickness of each geological layer and the excavation equipment, determine the work efficiency assignment of each geological layer and excavation equipment;

(3) Select the excavation equipment for each geological layer according to the above-mentioned work efficiency.

In the method for selecting the excavation equipment for the excavation equipment of the subway station containing weathered sandstone, preferably, according to the matching relationship between the rock and soil strength and thickness of each geological layer and the excavation equipment, the work efficiency assignment of each geological layer and the excavation equipment includes: The following steps:

S1: Determine the assigned score X of the pressure factor, where, X=P0/P1*k; where: X is the assigned score of the pressure factor, P0 is the applicable pressure of the excavation equipment, P1 is the average rock and soil strength of each geological layer, k is a coefficient, when the ratio of P0/P1 is within 40 times, k is (1/2)^n, otherwise k is 0, and when the ratio of P0/P1 is (0-10], n is 0, when P0/P1 When the ratio is (10-21], n is 1; when the P0/P1 ratio is (21-30], n is 2; when the P0/P1 ratio is (30-40), n is 3;

S2: Determine the thickness factor assignment score Y, specifically, first calculate H1/H0, if the decimal part of H1/H0 is 0, take 3 points, if the decimal part of H1/H0 is (0-0.5], take 1 point, H1/H0 The fractional part of H1/H0 is (0.5-0.75), 2 points are taken, and the fractional part of H1/H0 is above 0.75, 3 points are taken; among them, Y is the score assigned to the thickness factor, H1 is the average thickness of each geological layer, and H0 is the excavation equipment. Economical excavation depth;

S3: adding the assigned score X of the pressure factor and the assigned score Y of the thickness factor to obtain the ergonomics assigned score.

In the method for selecting the excavation equipment for the excavation equipment of the subway station foundation pit containing weathered sandstone, preferably, the applicable pressure of the excavation equipment is considered according to the most unfavorable pressure factor of the excavation equipment. The unfavorable factor is high-pressure rock and soil, and the most unfavorable factor for hydraulic breakers, hydraulic splitters and static blasting equipment is low-pressure rock and soil. That is, in the present invention, grabbing machine, excavator and hook machine are calculated according to the maximum applicable pressure, and hydraulic breaker, hydraulic splitter and milling machine and static blasting equipment are calculated according to the minimum applicable pressure.

Aiming at the foundation pit of subway stations containing weathered sandstone, the present invention proposes a set of theoretical systems for selecting the optimal excavation equipment corresponding to each geological layer based on the matching relationship between the strength and thickness of rock and soil of each geological layer and the excavation equipment, and innovates The complex relationship between rock and soil strength, thickness and excavation equipment is given definitively, and a set of methods for selecting excavation equipment suitable for each foundation pit is established, which is conducive to the selection of optimal excavation equipment, and can be widely used in civil construction process.

In the above method for selecting excavation equipment for subway station foundation pits containing weathered sandstone, it is preferable to consider the additional score value of the excavation equipment when selecting excavation equipment for each geological layer according to the level of work efficiency assignment. The excavation equipment for each geological layer is selected based on the sum of the additional score values of the excavation equipment; the additional score value of the excavation equipment is determined according to the excavation efficiency, transportation auxiliary facilities, auxiliary material consumption, construction environmental conditions and unit price of equipment per shift . In the present invention, the specific determination methods of the excavation efficiency of each excavation equipment, transportation auxiliary facilities, auxiliary material consumption, construction environmental conditions and unit price of each equipment shift are shown in Table 8 below. The present invention proposes the concept of additional score value for excavation equipment for foundation pits of subway stations containing weathered sandstone, and clarifies each excavation equipment in terms of excavation efficiency, transportation auxiliary facilities, auxiliary material consumption, construction environment conditions and equipment shifts. The specific score value of these aspects of unit price is conducive to the selection of more reasonable excavation equipment.

In the method for selecting the excavation equipment for the excavation equipment of the subway station foundation pit containing weathered sandstone, preferably, the excavation equipment is a grab machine with a bucket capacity of 1.5m3, a single bucket excavator with a bucket capacity of ^1.6m3 , and a ⁶ -ton hook machine , Flat head and round head drill rod hydraulic breaker with a chassis weight of more than 17 tons, 30-type hydraulic splitter and milling machine and static blasting equipment. In the present invention, see Table 1 below for the specific parameters of the above-mentioned excavation equipment.

In the method for selecting excavation equipment for foundation pits of subway stations containing weathered sandstone, preferably, the applicable pressure range of the excavator is <2MPa, the economical excavation depth H0 is 1.8m, and the applicable pressure range of the excavator is <10MPa. The economical excavation depth H0 is 1.2m, the applicable pressure range of the hook machine is <11MPa, the economical excavation depth H0 is 0.4m, the applicable pressure range of the hydraulic breaker is 30-60MPa, and the economical excavation depth H0 is 0.6 m, the applicable pressure range of the hydraulic splitter milling machine is 20-50MPa, the economical excavation depth H0 is 0.3m, the applicable pressure range of the static blasting equipment is >30MPa, and the economical excavation depth H0 is 1.8m.

In the method for selecting the excavation equipment of the subway station foundation pit containing weathered sandstone, preferably, the geological layers are plain fill layer, gravel layer, strongly weathered layer, moderately weathered layer and slightly weathered layer from top to bottom. The average rock-soil strength of the plain filling layer is 0.49MPa, and the average thickness is 2.95m. The average rock-soil strength of the gravel layer is 0.4MPa, and the average thickness is 0.85m. The average rock-soil strength of the strong weathered layer is 0.94MPa, with an average thickness of 4.18m. The average rock-soil strength of the medium weathered layer is 6.28MPa, and the average thickness is 11.69m. The average rock-soil strength of the slightly weathered layer is 20MPa, and the average thickness is 2.93m.

Compared with the prior art, the present invention has the advantages of:

The present invention aims at the foundation pit of a subway station containing weathered sandstone, establishes geological conditions and optional equipment configuration tables before excavation of the foundation pit, analyzes various excavation schemes, performs combination and comparison, and obtains the optimum scheme of engineering value. This method establishes a more scientific program selection system, which can be objectively and quantitatively selected to achieve the optimal value of the project. It reduces the selection errors of human limitations, avoids waste of resources, and supports safe and efficient construction of the project.

Detailed ways

In order to facilitate the understanding of the present invention, the following will describe the present invention more fully and in detail in combination with preferred embodiments, but the protection scope of the present invention is not limited to the following specific embodiments.

Unless otherwise defined, all technical terms used hereinafter have the same meanings as commonly understood by those skilled in the art. The terminology used herein is only for the purpose of describing specific embodiments, and is not intended to limit the protection scope of the present invention.

Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

Example 1:

A method for selecting excavation equipment for a subway station foundation pit containing weathered sandstone, comprising the following steps:

(1) Investigate and determine the geological conditions before the excavation of the foundation pit of the subway station, and determine the geological layers included in the geology;

(2) According to the matching relationship between the rock and soil strength and thickness of each geological layer and the excavation equipment, determine the work efficiency assignment of each geological layer and excavation equipment;

(3) Determine the additional score value of the above-mentioned excavation equipment from the excavation efficiency, transportation auxiliary facilities, auxiliary material consumption, construction environment conditions and equipment shift unit price;

(4) Determine the excavation equipment selected for each geological layer according to the above-mentioned work efficiency assignment and additional score value.

In order to better illustrate the selection method of excavation equipment for the excavation of the subway station containing weathered sandstone, this embodiment takes a station of Changsha subway as an example to illustrate the steps of the above selection method as follows:

1. Survey and confirm the geological conditions before excavation of the foundation pit of the subway station. It is determined that the geological layers included in the geology are plain fill soil layer (rock-soil strength 0.49MPa, thickness 2.95m), gravel layer (rock layer) from top to bottom. Soil strength is 0.4MPa, thickness is 0.85m), strongly weathered layer (rock-soil strength is 0.94MPa, thickness is 4.18m), medium weathered layer (rock-soil strength is 6.28MPa, thickness is 11.69m) and slightly weathered layer ( The strength of rock and soil is 20MPa, and the thickness is 2.93m). The strength and thickness of the above rock and soil are uniform and the average value is measured by sampling at multiple points.

2. Determine the scope of application of various types of excavation equipment under the working conditions of the foundation pit of the subway station, as shown in Table 1 below.

Table 1: Scope of application of excavation equipment

3. According to the matching relationship between the rock and soil strength and thickness of each geological layer and the excavation equipment, determine the work efficiency assignment of each geological layer and excavation equipment

3.1 Scoring calculation of rock and soil pressure factors

Considering the most unfavorable pressure factor of excavation equipment, the ratio of the applicable pressure of excavation equipment to the strength of rock and soil is assigned as the score; Milling machines and static blasting equipment require a certain pressure in the rock and soil to work effectively, and low rock and soil pressure is the most unfavorable factor. The calculation formula for the above-mentioned rock and soil pressure factor assignment is: X=P0/P1*k; where: X is the assigned score of the pressure factor; P0 is the applicable pressure of the excavation equipment (the maximum applicable pressure Calculation, hydraulic breaker, hydraulic splitter and static blasting equipment are calculated according to the minimum applicable pressure); P1 is the average rock and soil strength of each geological layer; k is a coefficient, when the ratio of P0/P1 is within 40 times, k is (1 /2)^n(1/2 to the nth power), otherwise k is 0. The value of n is shown in Table 2 below, the ratio of P0/P1 is shown in Table 3 below, and the final pressure factor assignment score X is shown in Table 4 below.

Table 2: n values

P0/P1 ratio multiple	(0-10)	(10-21)	(21-30】	(30-40)
no	0	1	2	3

Table 3: Ratio of P0/P1

device name	Plain fill layer	gravel layer	strong regolith	middle regolith	microregolith
seize the opportunity	4.1	5.0	2.1	0.3	0.1
Excavator	20.4	25.0	10.6	1.6	0.5
hook machine	22.4	27.5	11.7	1.8	0.6

hydraulic breaker	61.2	75.0	31.9	4.8	1.5
Hydraulic splitter	40.8	50.0	21.3	3.2	1.0
static blasting equipment	61.2	75.0	31.9	4.8	1.5

Table 4: Score assigned to rock and soil pressure factors X

device name	Plain fill layer	gravel layer	strong regolith	middle regolith	microregolith
seize the opportunity	4.1	5.0	2.1	0.3	0.1
Excavator	10.2	6.3	5.3	1.6	0.5
hook machine	5.6	6.9	5.9	1.8	0.6
hydraulic breaker	0.0	0.0	4.0	4.8	1.5
Hydraulic splitter	0.0	0.0	5.3	3.2	1.0
static blasting equipment	0.0	0.0	4.0	4.8	1.5

3.2 Scoring calculation of rock and soil thickness factors

The thickness that affects the selection of excavation equipment is the part that is less than one layer thick. According to this method, we first calculate the ratio of the thickness of the rock and soil layer H1 to the economic excavation depth H0 of the excavation equipment, as shown in Table 5 below. Integer part in table 5 is the excavation layer number, is not the influencing factor of equipment selection in the present invention, only has the fractional part of less than one layer thickness to have influence, so with the decimal part in table 5 as base number calculation assigning, decimal part is 0 Take 3 points, (0-0.5] take 1 point, (0.5-0.75] take 2 points, and 0.75 or more take 3 points, and then get the assigned score Y of the rock and soil thickness factor, as shown in Table 6.

Table 5: Ratio of rock and soil layer thickness H1 to equipment economical excavation depth H0

Table 6: Score Y assigned to rock and soil thickness factors

3.3 Ergonomic assignment of geological layers and excavation equipment

From the sum of the assigned score X of the pressure factor in Table 4 and the assigned score Y of the rock-soil thickness factor in Table 6, the work efficiency score Z of each geological layer and excavation equipment is obtained, as shown in Table 7 below.

Table 7: Ergonomic Score Z

4. Determine the additional score values corresponding to the above excavation equipment from the perspective of excavation efficiency, transportation auxiliary facilities, auxiliary material consumption, construction environment conditions and unit price of each equipment shift. The specific determination rules for additional score values are as follows:

Excavation function: Use soft rock and compact rock and soil to select equipment. Soft rock and soil are processed by grabs, excavators and hook machines, and dense rock and soil are processed by hydraulic breakers, hydraulic splitters and static blasting equipment. In soft rock and soil, the ranking of excavation efficiency is that the excavator is better than the grab machine, and the grab machine is better than the hook machine. Hydraulic breaker.

Transportation auxiliary facilities: Grabbers and excavators do not need to be equipped with transportation auxiliary facilities. However, the grab machine is placed on the foundation pit and can move along the periphery of the foundation pit, which is conducive to vertical transportation in the foundation pit, and is suitable for foundation pits with small widths; The excavation progress is affected, and it is suitable for foundation pits with large width and moderate length. Therefore, the grab machine is better than the excavator. Other equipment needs to be equipped with shipping auxiliary facilities, which are worse than grabbers and excavators.

Auxiliary material consumption: Static blasting equipment consumes a lot of auxiliary materials, hydraulic splitting and milling machines need to replace tools, and the consumption is medium. The material consumption of grabbers and excavators is equivalent to that of hydraulic splitting and milling machines, and the consumption of hook machines and hydraulic breakers is the smallest.

Construction environment conditions: when excavating a long foundation pit with a machine, it is necessary to reserve a passage on the top of the foundation pit, but it is not sensitive to the accumulation of water in the foundation pit; there is no requirement for the passage on the top of the foundation pit when digging with an excavator, but there must be a transportation horseway in the foundation pit Or multiple excavators for relay excavation or adding vertical transport equipment; static blasting equipment has requirements for ambient temperature and whether it rains; other equipment is not restricted. Therefore, the static blasting equipment should be the highest, followed by the grabbing machine and excavator, and there is no requirement for other equipment.

The unit price of equipment per shift: static blasting equipment is the lowest per shift unit, followed by hook machines, and other equipment is equivalent but higher than hook machines.

Among the above-mentioned influencing factors, 2 points are given for being in a dominant position, 0 points for being in a disadvantaged position, and 1 point for otherwise; the excavation efficiency of soft rock and soil is reduced by a coefficient of 0.6. The specific additional score value of each device is shown in Table 8 below.

Table 8: Additional score value W

Controlling factor	seize the opportunity	Excavator	hook machine	hydraulic breaker	Hydraulic splitter	static blasting equipment
Excavation effect	0.6	1.2	0	0	1	2
transportation aids	2	1	0	0	0	0
Auxiliary material consumption	1	1	2	2	1	0
Construction environment conditions	1	1	2	2	2	0
Unit price of equipment per shift	0	0	1	0	0	2
average score	0.9	0.8	1	0.8	0.8	0.8

5. The comprehensive work efficiency score Z and the additional score value W, the sum of which is the comprehensive score K of the excavation equipment. The comprehensive score K of the excavation equipment corresponding to each geological layer is shown in Table 9 below.

Table 9: Composite Score K

6. According to the above comprehensive score K, the equipment selection for each geological layer is as follows:

The plain fill is mainly cohesive soil, partially containing gravel; the silty clay can be in plastic to hard plastic state, containing a small amount of fine sand, mica flakes and black iron and manganese oxides; excavators and hooks can be selected according to the work efficiency. A digging machine or a grabbing machine, more preferably, an excavating machine or a hooking machine can be selected according to the comprehensive score K, and more preferably, an excavating machine is used.

The gravel layer is mainly filled with medium-coarse sand, with a mud content of 10%, poor sorting, and good grading; according to the work efficiency Z, you can choose excavator, hook machine or grab machine, and more preferably, according to the comprehensive score K, An excavator or a hook machine can be selected, and further preferably, an excavator is used.

The strongly weathered argillaceous siltstone has a silty structure, medium-thick layered structure, muddy cementation, poor cementation, broken core, easy to soften after soaking in water, and is an extremely soft rock; strong weathered conglomerate is partially interbedded with thin layers of argillaceous powder Sandstone, clastic structure, massive structure, muddy cementation, joints and fissures developed, rock mass broken, rock cores are mostly fragmented to massive; hydraulic splitting milling machine, hydraulic breaker or hook can be selected according to work efficiency Z machine, more preferably, according to the comprehensive score K, you can choose a hydraulic splitter or hook machine, and more preferably, a hydraulic splitter.

The moderately weathered argillaceous siltstone has a silty structure, a medium-thick layered structure, muddy cementation, and a relatively complete core; according to the work efficiency assignment Z, hydraulic splitting and milling machines, hydraulic breakers or static blasting equipment can be selected, more preferably , according to the comprehensive score K, you can choose hydraulic splitting and milling machine, hydraulic breaker or static blasting equipment, and more preferably, use hydraulic splitting and milling machine.

Micro-weathered quartz sandstone and feldspar sandstone are composed of quartz and feldspar main particles, the debris is mostly angular or sub-angular, the cement is mostly carbonate or iron, and the strength of the rock formation has a large transition; Z can be assigned according to the work efficiency Choose hydraulic breaker, hydraulic splitter or static blasting equipment, more preferably, according to the comprehensive score K, you can choose hydraulic breaker or hydraulic splitter, more preferably, use hydraulic breaker.

Please refer to Table 1 for the models of the above-mentioned specific equipment, and one decimal point is reserved for the calculation process of all the above-mentioned scores.

Claims (7)

1. A method for selecting excavation equipment for a subway station foundation pit containing weathered sandstone, characterized in that it includes the following steps:

   (1) Investigate and determine the geological conditions before the excavation of the foundation pit of the subway station, and determine the geological layers included in the geology;

   (2) According to the matching relationship between the rock and soil strength and thickness of each geological layer and the excavation equipment, determine the work efficiency assignment of each geological layer and excavation equipment;

   (3) Select the excavation equipment for each geological layer according to the above-mentioned work efficiency.
2. The method for selecting excavation equipment for foundation pits of subway stations containing weathered sandstone according to claim 1, characterized in that, according to the matching relationship between the rock and soil strength and thickness of each geological layer and the excavation equipment, it is determined that each geological layer and excavation The ergonomics assignment of equipment includes the following steps:

   S1: Determine the assigned score X of the pressure factor, where, X=P0/P1*k; where: X is the assigned score of the pressure factor, P0 is the applicable pressure of the excavation equipment, P1 is the average rock and soil strength of each geological layer, k is a coefficient, when the ratio of P0/P1 is within 40 times, k is (1/2)^n, otherwise k is 0, and when the ratio of P0/P1 is (0-10], n is 0, when P0/P1 When the ratio is (10-21], n is 1; when the P0/P1 ratio is (21-30], n is 2; when the P0/P1 ratio is (30-40), n is 3;

   S2: Determine the thickness factor assignment score Y, specifically, first calculate H1/H0, if the decimal part of H1/H0 is 0, take 3 points, if the decimal part of H1/H0 is (0-0.5], take 1 point, H1/H0 The fractional part of H1/H0 is (0.5-0.75), 2 points are taken, and the fractional part of H1/H0 is above 0.75, 3 points are taken; among them, Y is the score assigned to the thickness factor, H1 is the average thickness of each geological layer, and H0 is the excavation equipment. Economical excavation depth;

   S3: adding the assigned score X of the pressure factor and the assigned score Y of the thickness factor to obtain the ergonomics assigned score.
3. The method for selecting excavation equipment for foundation pits of subway stations containing weathered sandstone according to claim 2, wherein the applicable pressure of the excavation equipment is considered according to the most unfavorable pressure factors of the excavation equipment, wherein the grabbing machine, excavation The most unfavorable factor of the machine and the hook machine is the high-pressure rock and soil, and the most unfavorable factor of the hydraulic breaker, the hydraulic splitter and the static blasting equipment is the low-pressure rock and soil.
4. The method for selecting excavation equipment for subway station foundation pits containing weathered sandstone according to claim 1, wherein the additional score value of the excavation equipment is also considered when selecting the excavation equipment for each geological layer according to the level of work efficiency assignment, The excavation equipment of each geological layer is selected according to the sum of the work efficiency and the additional score value of the excavation equipment; And the unit price of equipment per shift is determined.
5. The method for selecting excavation equipment for foundation pits of subway stations containing weathered sandstone according to any one of claims 1-4, wherein the excavation equipment is a grab machine with a bucket capacity ^of 1.5m and a bucket capacity of 1.6m ³ single-bucket excavators, 6-ton hook machines, flat-head and round-head drill rod hydraulic breakers with a chassis weight of more than 17 tons, 30-type hydraulic splitters and milling machines, and static blasting equipment.
6. The method for selecting excavation equipment for subway station foundation pits containing weathered sandstone according to claim 5, characterized in that, the applicable pressure range of the grabbing machine is <2MPa, the economical excavation depth H0 is 1.8m, and the excavating machine's The applicable pressure range is <10MPa, the economical excavation depth H0 is 1.2m, the applicable pressure range of the hook machine is <11MPa, the economical excavation depth H0 is 0.4m, and the applicable pressure range of the hydraulic breaker is 30-60MPa, economical The excavation depth H0 is 0.6m, the applicable pressure range of the hydraulic splitter milling machine is 20-50MPa, the economical excavation depth H0 is 0.3m, the applicable pressure range of the static blasting equipment is > 30MPa, and the economical excavation depth H0 is 1.8m.
7. The method for selecting excavation equipment for subway station foundation pits containing weathered sandstone according to any one of claims 1-4, wherein the geological layers are plain fill layer, gravel layer, and strong wind layer from top to bottom. The average rock-soil strength of the plain fill layer is 0.49MPa, and the average thickness is 2.95m. The average rock-soil strength of the gravel layer is 0.4MPa, and the average thickness is 0.85m. , the average rock-soil strength of the strongly weathered layer is 0.94MPa, the average thickness is 4.18m, the average rock-soil strength of the described medium weathered layer is 6.28MPa, and the average thickness is 11.69m, the average rock-soil strength of the described slightly weathered layer The strength is 20MPa, and the average thickness is 2.93m.