RU2449075C1 - Method to strengthen loose natural base for erection of road earth bed - Google Patents

Method to strengthen loose natural base for erection of road earth bed Download PDF

Info

Publication number
RU2449075C1
RU2449075C1 RU2010148128/03A RU2010148128A RU2449075C1 RU 2449075 C1 RU2449075 C1 RU 2449075C1 RU 2010148128/03 A RU2010148128/03 A RU 2010148128/03A RU 2010148128 A RU2010148128 A RU 2010148128A RU 2449075 C1 RU2449075 C1 RU 2449075C1
Authority
RU
Russia
Prior art keywords
soil
base
piles
pile
vibration
Prior art date
Application number
RU2010148128/03A
Other languages
Russian (ru)
Inventor
Святослав Яковлевич Луцкий (RU)
Святослав Яковлевич Луцкий
Василий Алексеевич Шмелев (RU)
Василий Алексеевич Шмелев
Алексей Юрьевич Бурукин (RU)
Алексей Юрьевич Бурукин
Original Assignee
Общество с ограниченной ответственностью "Финансово-Строительная компания "МостГеоЦентр"
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Общество с ограниченной ответственностью "Финансово-Строительная компания "МостГеоЦентр" filed Critical Общество с ограниченной ответственностью "Финансово-Строительная компания "МостГеоЦентр"
Priority to RU2010148128/03A priority Critical patent/RU2449075C1/en
Application granted granted Critical
Publication of RU2449075C1 publication Critical patent/RU2449075C1/en

Links

Images

Abstract

FIELD: construction, road engineering.
SUBSTANCE: invention relates to construction of earth works erected on loose natural bases, including a road earth bed, preferably for a railway or a motor road. The method to strengthen a loose natural base to erect a road earth bed on collapsing soils of high capacity includes arrangement of a reinforcement device in a loose base soil in the form of ground piles, every of which represents a protective shell filled with a draining material, and subsequent surface vibratory compaction in a controlled mode with filling of sand or sand and gravel mixture between piles into a pile-to-pile space reinforced with a textile fabric, besides, control of the vibratory compaction mode by variation of vibration load parameters is carried out depending on condition of deformation and strength characteristics of a compacted soil determined as a result of systematic calculation of a soil safety coefficient, and monitoring stresses in the pile-to-pile space from vertical loads that occur in process of vibratory compaction and horizontal load that occur as soil piles expand in a protective shell. To speed up consolidation of the base soil and reduce time of soil subsidence in process of surface vibratory compaction of the pile-to-pile space, the vibration load parameters are varied until the soil safety coefficient reaches the maximum possible value of load against the base, and are maintained at a level permissible by the safety coefficient value.
EFFECT: higher reliability of earth bed base due to its strengthening (reinforcement) in the controlled mode.
3 cl, 1 dwg

Description

The invention relates to the construction of erected on weak natural foundations earthworks, including road subgrade, mainly for rail or road.
At present, to strengthen and increase the strength of weak bases of high power, various technologies are used to arrange piles and deep compaction of subsidence soils.
Known methods of constructing a roadbed on a weak foundation with the device using a drilling or driving method of pile-drains, concrete or cement-hard ground piles and laying in the upper part of the pile base of geotextile, performing the function of a flexible grill [1].
These methods have the following disadvantages:
- significant cement consumption in the construction of pile reinforced concrete structures;
- loss of bulk piles and piles-drains in the soil under load form and, accordingly, bearing capacity;
- uneven settlement and breaks of geotextiles due to different bearing capacity of piles and inter-pile space.
In addition, the installation of sandy gravel piles provides only filtration consolidation, but not soil consolidation, which is possible only with its additional compaction.
A known method of hardening a weak base [2], including the installation of sand piles in a protective sheath made of geosynthetic material by immersing a weak base of casing pipes into the ground, constructing a protective shell inside the pipes, portioning the sand inside the shell, compacting each portion and subsequently removing the casing pipes. Hardening of the weak base is achieved due to lateral expansion of the sand piles during vibration casing of the casing and subsequent vibration compaction of sand in the protective sheath. The disadvantage of this method is the low bearing capacity of the inter-pile space and, as a consequence, the uneven settlement of piles and soil in the inter-pile space and the breaks of the geosynthetic material. To strengthen the base with this method, it is necessary to reduce the distance between piles. This drawback is due to the lack of grillage or other structural and technological solutions that strengthen the base in the inter-pile space.
The closest in the set of essential features is the well-known (RU, patent [3] No. 2337205 C1) method of erecting an earthen structure on weak natural foundations, including the implementation of a weak base of a reinforcing device in the soil by constructing soil piles in combination with surface vibration compaction of the soil from the surface of the base.
The main disadvantages of this method, preventing the receipt of the following technical result:
1) loss of sand or gravel piles in the ground under the form load and, accordingly, bearing capacity due to the lack of a protective shell and redistribution of the load mainly on the piles;
2) the deformation of piles in the soil under the action of internal filtration and dynamic loads due to different strengths of the base (piles and inter-pile space work in different compression and deformation modes.
3) significant upsetting between the piles.
The objective of the present invention is to improve the safety of earthworks in areas of subsidence of subsidence soils.
The technical result that can be obtained as a result of the implementation of the invention is to increase the reliability of the foundation of the earthworks due to its hardening (strengthening) in a controlled mode.
The specified technical result is achieved due to the fact that the method of hardening a weak natural foundation for the construction of road subgrade on high-power subsiding soils includes the construction of a weak base reinforcing device in the form of soil piles, each of which is a protective shell filled with drainage material, and subsequent surface vibration compaction in an adjustable mode with sending between piles of sand or sand-gravel mix reinforced with geotextiles of water, moreover, the vibration compaction mode is regulated by changing the parameters of the vibration load depending on the state of deformation and strength characteristics of the compacted soil, determined as a result of a systematic calculation of the soil safety coefficient (Kbez.), and monitoring stresses from vertical loads arising in vibration compaction in the inter-pile space , and horizontal loads resulting from the expansion of soil piles in the protective sheath.
To accelerate the consolidation of the soil of the base and reduce the time of soil settlement during the surface vibration compaction of the inter-pile space, the parameters (vibration amplitude and speed of the roller) of the vibration load are changed until the maximum allowable safety factor of the soil reaches the load value (from the combined effects of horizontal and vertical loads) on the base and support them at an acceptable value of the safety factor (K without.> 0.2) level.
The greater the load, the faster the filtration, sediment and increase in the strength of the soil between the piles.
In this process control includes:
1) application to the weak base of the maximum allowable load from the vibratory roller (vertical load),
2) monitoring stresses from vertical and horizontal loads and calculating the safety factor,
3) a change in the thickness of the protective layer, the amplitude of the vibration, the speed of the roller, the time of compaction of the base through the protective layer;
4) control of soil characteristics: moisture, adhesion, angle of internal friction.
A systematic calculation of the safety factor and the determination of the corresponding vertical load mode in magnitude (weight of the vibratory roller, vibration amplitude) and exposure time is necessary for the stability of the soil mass at elevated vibration loads.
With a decrease in the actual Kbez. Compared with its permissible value according to the norms (the bearing capacity of the modified base depends on the characteristics of the base soil) they reduce the vertical load and take technological breaks in the work schedule.
The hardened base obtained as a result of the implementation of the inventive method is a composite structure combining soil piles in a protective sheath and a compacted geo-drill. The design ensures the joint work of piles and a compacted inter-pile space due to the uniform distribution of load on the base.
During the formation of a geos pile grillage, a decrease (in magnitude and time) of potential sedimentation of the base occurs due to an increase in its deformation modulus.
In the process of soil compaction in the inter-pile space, soil sedimentation is completed, moisture is reduced and the filtration consolidation of the soils is accelerated, the strength characteristics of the soils of the weak base are increased during the construction period, and the load of the embankment is rejected to accelerate the settlement of the soil.
A compacted geo-drill is formed in the upper part of soils of a weak base directly in the inter-pile space during regulation (in time and size) under the control of the safety factor of the compacted soil array of vibration loads: vertical - from intensive compaction with a vibratory roller, and horizontal from expansion of soil piles in the protective sheath.
In soils with a fluid-plastic consistency (fluid-plastic soils), surface vibration compaction of the base is carried out before the reinforcing device is made. In this case, the protective layer is arranged by sliding sand onto a weak base. This method provides the passage of copra for the device piles.
As a rule, before performing a weak base of the reinforcing device in the soil, drainage slots are constructed and a protective technological layer is arranged. After completing the reinforcing device and surface vibration compaction of the inter-pile space, which is carried out with a backfill between piles of sand or a sand-gravel mixture, a layer of geotextile is arranged on the bottom of the embankment, and then the embankment is filled and compacted.
The principal novelty of the technical solution is the regulation and control of horizontal and vertical loads in the inter-pile space in order to form a compacted geo-drill, which provides soil hardening and joint work of the pile bush in a protective sheath. The method can also be used in the construction of dams, dams, etc.
The essence of the present invention is illustrated by the figure, which shows the transverse profile of the embankment of the roadway with the placement of geo-piles and the distribution of loads in the inter-pile space: horizontal (RG) - from the expansion of the pile in the protective shell and vertical (RV) - from the vibratory roller with intensive compaction of the base. The figure indicates: 1 - planned base; 2 - geo-pile in a protective shell; 3 - drainage ditch, 4 - slot (trench filled with sand or gravel); 5 - geotextile layer intended for the separation of soil, georeferencing and embankment, as well as water drainage; 6 - embankment.
The proposed sequence of work to strengthen the weak base includes the following steps.
The first stage is the layout of the site, the installation of drainage ditches and slots, the device of the protective technological layer - the working platform (technological berm (passage) for moving cars and people). Slots are arranged in weak water-saturated soils in accordance with the recommendations [4] in order to accelerate the consolidation (sediment, compaction of the base) of the base by reducing the filtering path of the water squeezed from a thin layer. The distance between the drainage slots is prescribed based on the filtration properties of soils. The width of the slots is assigned 1 - 1.2 m, depending on the equipment used for the device of the slots. To fill the slots should use gravel sand with a filtration coefficient K f > 4 m / day or gravel.
The second stage is the construction in the soil of the base of the reinforcing device - piles in a geotextile protective sheath with a distance between them of 2 - 2.5 m using vibration equipment and drilling rigs by the method of displacing or sampling the soil.
The protective shell is filled with sand or other draining material, usually in bulk portions. Due to the lateral expansion of the flexible shell, the initial compaction of the soil occurs in the inter-pile space.
The protective shell is a round-woven seamless sleeve made of synthetic material with a diameter of 0.6-1.5 m (for example, manufactured by KARDARNA (Czech Republic) or HUESKER (Germany)).
The distances between piles are determined by calculations and depend on the type of soil of the base and the expected load. Reducing the distance between piles increases the bearing capacity, but increases the consumption of materials.
In contrast to the prototype, in the proposed technical solution for hardening the base, they organize the combined effect of horizontal loads from geo-piles in the protective sheath and vertical loads with adjustable compaction of the inter-pile space with a vibratory roller.
Therefore, the third step of the method is the preparation of the base for vibration compaction in an adjustable mode — base reinforcement: the installation of a geotextile layer over piles.
The fourth stage is surface vibration compaction of a weak base in an adjustable mode: a change in vibration compaction mode depending on the quality of soil compaction, characterized by the state of its deformation and strength characteristics, which are determined as a result of a systematic calculation of the safety factor and monitoring of vertical stresses arising from vibration compaction in the inter-pile space , and horizontal loads resulting from the expansion of the geological pile in the protective sheath.
Surface vibration compaction of a weak base in an adjustable mode is carried out in order to increase the strength characteristics and stability of the base soils by consolidating the base soils for joint work of piles and the inter-pile space, increasing the base settlement during the construction period, eliminating pile overload and their deformation.
During the settlement of the technological protective layer, to ensure the passage of the sealing machines and to exclude damage to the shell of the piles, they add sand between the piles. As a result, a compacted grillage is formed, which ensures the joint work of piles and soil in the inter-pile space under load.
Fifth stage - on a prepared base, arrange a layer of geotextile on the bottom of the embankment and begin layered filling and compaction of the embankment.
The experimental application of individual stages of the composite technology [4] showed that compaction of soft-plastic loam with a heavy vibratory roller with a combined effect of weight and disturbing force of more than 300 kN leads to accelerated settlement: it gives about 60% of the total settlement of a layer 3 m thick in 5 days and the completion of design settlement 3 months.
Example.
Safety factor for a layer of weak base Кbez = Р without / Р calculation , where Р without - the safe load for the controlled layer depends on soil characteristics (density, adhesion, angle of internal friction) t / sq.m; R calculation - total design (horizontal - from the expansion of the geoshaft sheath and vertical - from the weight of the soil and the vibratory roller) load, t / m 2 .
According to the standards [1], if the actual value of the safety factor is more than unity, then the stability of the embankment design is ensured. In the range of coefficient values from 0.2 to 1, embankment filling is allowed at a slow loading rate of the base. If the safety factor is 0.2 or less, then the stability of the earthen structure is not ensured; it is necessary to change the technological regimes and strengthen the structure.
When arranging road approaches to the Kama railroad bridge (base soil - fluid-plastic loam), an intensive compaction technology was applied through a protective layer of 0.5 m. The safe load for a weak base layer was 7.2 t / m2. To compact the base, a Dinapak skating rink was provided, having a vibratory drum weight of 5.6 tons with a driving force of 246 kN and 119 kN, respectively, at the 1st and 2nd stage (amplitude) of vibration. The calculated load for the weak layer from the weight of the soil and the vibratory roller at the 1st and 2nd stage of vibration was 10.5 t / sq.m and 7 t / sq.m, respectively. According to the monitoring results, the safety factor during compaction with the 1st stage of vibration was Kbez = 7.2 / 10.5 = 0.7. When the skating rink enters the 2nd stage vibration mode, Kbez = 7.2 / 7 = 1.02, which corresponds to a safe method of hardening a weak base.
If the control of the operation parameters of the vibratory roller does not provide the limiting value of Kbez, then to increase the safety of the weak base, an increase in the thickness of the protective layer from 0.4 m to 0.8 m is used.
LITERATURE
1. Design, construction, operation of roads and airfields. - Proceedings of the Union Health, issue 205. M., 2005.
2. Kempfert H.-G., Stadel M., Zaeske D .: Berechnung von geokunststoffbewehrten Tragschichten über Pfahlelementen / Bautechnik. Vol 74, No.12, 1997.
3. Lutsky S.Ya., Dolgov D.V., Sudakov D.V. The method of construction of an earthen structure on weak grounds // Patent No. 2337205, 2008.
4. Recommendations on intensive technology and monitoring the construction of earthworks on weak grounds // Ed. prof. Lutsky S.Ya. - M .: TIMR, 2005.

Claims (3)

1. A method of hardening a weak natural base for the construction of a road subgrade, including the construction in the ground of a weak base of a reinforcing device in the form of soil piles, each of which is a protective shell filled with drainage material, and subsequent surface vibration compaction in an adjustable mode with filling between piles of sand or sand-gravel mixture reinforced with geotextile interspace, moreover, the regulation of vibration compaction by changing the parameters of vibra translational load produced depending on the state of deformation and strength characteristics of compacted soil determined in a systematic calculation safety factor soils and monitoring mezhsvaynom stress space from vertical loads arising during vibration compaction and horizontal loads produced during expansion of ground piles within the protective shell.
2. The method according to claim 1, characterized in that the parameters of the vibration load are changed until the maximum allowable safety factor of the soil reaches the load on the base and support them at an acceptable level of safety factor.
3. The method according to any one of claims 1 and 2, characterized in that in the fluid-plastic soils prior to the reinforcing device, a drainage slot, a protective layer and surface vibration sealing of the base are produced.
RU2010148128/03A 2010-11-26 2010-11-26 Method to strengthen loose natural base for erection of road earth bed RU2449075C1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
RU2010148128/03A RU2449075C1 (en) 2010-11-26 2010-11-26 Method to strengthen loose natural base for erection of road earth bed

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
RU2010148128/03A RU2449075C1 (en) 2010-11-26 2010-11-26 Method to strengthen loose natural base for erection of road earth bed

Publications (1)

Publication Number Publication Date
RU2449075C1 true RU2449075C1 (en) 2012-04-27

Family

ID=46297523

Family Applications (1)

Application Number Title Priority Date Filing Date
RU2010148128/03A RU2449075C1 (en) 2010-11-26 2010-11-26 Method to strengthen loose natural base for erection of road earth bed

Country Status (1)

Country Link
RU (1) RU2449075C1 (en)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103774514A (en) * 2014-01-10 2014-05-07 江苏中瑞路桥建设有限公司 Prefabricated tube pile embankment structure and construction method thereof
RU2536538C1 (en) * 2013-07-18 2014-12-27 Виктор Анатольевич Бабелло Method for reduction of deformations of motor and railway roads on permafrost soils that thaw out in process of operation
RU2556646C1 (en) * 2014-05-19 2015-07-10 Виктор Анатольевич Бабелло Method to prevent deformations of linear structures erected on landslide slopes or manmade slopes on melting permafrost soils
RU2581851C1 (en) * 2015-03-31 2016-04-20 Акционерное общество "Научно-исследовательский институт железнодорожного транспорта" Method for reinforcement of linear objects on sink hole-hazardous areas
RU2593282C1 (en) * 2015-05-26 2016-08-10 Федеральное государственное бюджетное образовательное учреждение высшего образования "Уральский государственный университет путей сообщения" (УрГУПС) Method for reinforcement of railway road bed on weak base
CN106192652A (en) * 2016-08-31 2016-12-07 四川省交通运输厅交通勘察设计研究院 A kind of high steep embankment ruggedized construction preventing differential settlement
RU2610440C1 (en) * 2015-12-08 2017-02-10 Юрий Александрович Варфоломеев Method for removing of negative friction from piles on grounds with highly compressible soils
CN107338686A (en) * 2017-07-13 2017-11-10 高军 A kind of Subgrade Filled Soil in High Speed Railway construction method
CN108221601A (en) * 2018-01-16 2018-06-29 中建市政工程有限公司 The roadbed construction method and its structure and equipment of aeolian sand section
CN108842805A (en) * 2018-06-16 2018-11-20 扬州大学 Geosynthetic reinforced pile supported embankments on soft soil pile-soil stress determines method
RU2681722C1 (en) * 2018-05-30 2019-03-12 Открытое Акционерное Общество "Российские Железные Дороги" Device for non-sedimentary embankments of high-speed network
RU2708769C1 (en) * 2018-11-29 2019-12-11 федеральное государственное бюджетное образовательное учреждение высшего образования "Южно-Российский государственный политехнический университет (НПИ) имени М.И. Платова" Protective transport system of road structures and method of its erection

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1270888A (en) * 1969-08-27 1972-04-19 Fudo Construction Co Apparatus for forming sand piles
EP0085742A1 (en) * 1982-02-05 1983-08-17 Teijin Limited Method for improving soft ground by sand drain method and cylindrical bag for use in same
RU2054502C1 (en) * 1993-11-15 1996-02-20 Санкт-Петербургский государственный архитектурно-строительный университет Method for making cement/soil piles in caved-in soils
RU2273687C1 (en) * 2005-02-24 2006-04-10 Святослав Яковлевич Луцкий Roadbed and roadbed forming method

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1270888A (en) * 1969-08-27 1972-04-19 Fudo Construction Co Apparatus for forming sand piles
EP0085742A1 (en) * 1982-02-05 1983-08-17 Teijin Limited Method for improving soft ground by sand drain method and cylindrical bag for use in same
RU2054502C1 (en) * 1993-11-15 1996-02-20 Санкт-Петербургский государственный архитектурно-строительный университет Method for making cement/soil piles in caved-in soils
RU2273687C1 (en) * 2005-02-24 2006-04-10 Святослав Яковлевич Луцкий Roadbed and roadbed forming method

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2536538C1 (en) * 2013-07-18 2014-12-27 Виктор Анатольевич Бабелло Method for reduction of deformations of motor and railway roads on permafrost soils that thaw out in process of operation
CN103774514A (en) * 2014-01-10 2014-05-07 江苏中瑞路桥建设有限公司 Prefabricated tube pile embankment structure and construction method thereof
CN103774514B (en) * 2014-01-10 2015-10-07 江苏中瑞路桥建设有限公司 A kind of prefabricated tubular pile embankment structure and construction method thereof
RU2556646C1 (en) * 2014-05-19 2015-07-10 Виктор Анатольевич Бабелло Method to prevent deformations of linear structures erected on landslide slopes or manmade slopes on melting permafrost soils
RU2581851C1 (en) * 2015-03-31 2016-04-20 Акционерное общество "Научно-исследовательский институт железнодорожного транспорта" Method for reinforcement of linear objects on sink hole-hazardous areas
RU2593282C1 (en) * 2015-05-26 2016-08-10 Федеральное государственное бюджетное образовательное учреждение высшего образования "Уральский государственный университет путей сообщения" (УрГУПС) Method for reinforcement of railway road bed on weak base
RU2610440C1 (en) * 2015-12-08 2017-02-10 Юрий Александрович Варфоломеев Method for removing of negative friction from piles on grounds with highly compressible soils
CN106192652A (en) * 2016-08-31 2016-12-07 四川省交通运输厅交通勘察设计研究院 A kind of high steep embankment ruggedized construction preventing differential settlement
CN107338686A (en) * 2017-07-13 2017-11-10 高军 A kind of Subgrade Filled Soil in High Speed Railway construction method
CN108221601A (en) * 2018-01-16 2018-06-29 中建市政工程有限公司 The roadbed construction method and its structure and equipment of aeolian sand section
RU2681722C1 (en) * 2018-05-30 2019-03-12 Открытое Акционерное Общество "Российские Железные Дороги" Device for non-sedimentary embankments of high-speed network
CN108842805A (en) * 2018-06-16 2018-11-20 扬州大学 Geosynthetic reinforced pile supported embankments on soft soil pile-soil stress determines method
CN108842805B (en) * 2018-06-16 2020-06-09 扬州大学 Pile-supported reinforced embankment pile soil stress determination method
RU2708769C1 (en) * 2018-11-29 2019-12-11 федеральное государственное бюджетное образовательное учреждение высшего образования "Южно-Российский государственный политехнический университет (НПИ) имени М.И. Платова" Protective transport system of road structures and method of its erection

Similar Documents

Publication Publication Date Title
CN106284011B (en) Roadbed construction method
CN103410167B (en) Three-dimensional reinforced rigid-soft composite ecological retaining wall and construction method
CN103074891B (en) Double-layer plastic sleeve bulk material and concrete stiffness core composite pile and construction method thereof
Arulrajah et al. Ground improvement techniques for railway embankments
CN102433876B (en) Multi-compartment casing composite pile and construction method thereof
Demir et al. Large scale field tests on geogrid-reinforced granular fill underlain by clay soil
CN101343852B (en) Method for filling highroad roadbed by waste steel slags
CN103233454B (en) Processing method of soaking, vacuum preloading and slurry injecting for sand piles of collapsible loess foundation
CN104278608B (en) The constructional method of a kind of highway embankment widened structure
Matsuoka et al. A new earth reinforcement method using soilbags
CN103628378B (en) One is highway widening embankment structure and construction method near water
CN106320123A (en) Construction method of soft soil roadbed
CN102747662A (en) Construction method for sand-filling subgrade
CN106703050A (en) Expansive soil road cutting side slope reinforced soil back-pressure seepage-preventive supporting structure and construction method thereof
CN203383119U (en) Novel widening structure of highway embankment
CN102966119B (en) Geogrid reinforced wall and construction method thereof
CN107905089A (en) A kind of reinforcement platform back of the body for preventing bumping at bridge-head and its construction method
CN105155558A (en) Combined retaining structure and construction method thereof
CN101509248B (en) Control road for differential settlement at exchanging position of road and structure
CN206385411U (en) It is a kind of to prevent the steep embankment ruggedized construction of height of differential settlement
CN107447770A (en) A kind of big open caisson of superelevation and construction method
CN204059124U (en) A kind of sand drain strong rammer grouting behind shaft or drift lining foundation reinforcing structure
CN101220589B (en) Soil engineering bag and method for dynamically squeezing and synthetically reinforcing soft groundwork
CN101598028A (en) Lining structure for super large section water-rich loess tunnel of high-speed railroad
CN101634143A (en) Method for treating spiral oil-extruding filling pile composite foundation in stratum containing soft clay

Legal Events

Date Code Title Description
MM4A The patent is invalid due to non-payment of fees

Effective date: 20151127