A method for studying deformation and failure mechanism of loess high fill

Abstract

The application discloses a loess high fill deformation and failure mechanism research method, which explores the whole process of deformation and failure of high fills in loess areas by means of indoor test, field monitoring and numerical simulation method, and proposes a seepage-deformation dynamic coupling theory model of loess water-high pressure coupling caused subsidence and sliding according to the principles of soil mechanics, plastic mechanics and variation, and belongs to the technical field of geological research. The loess high fill deformation and failure mechanism research method comprehensively adopts multiple InSAR technologies to obtain large-scale, long-sequence and massive three-dimensional deformation data of multiple high fills in loess areas, studies the influence law of different factors on deformation through a big data deep learning method, inverses the deformation parameters of soil bodies under large loads, solves the problem of selection of deformation calculation parameters of high fills in airports, identifies deformation mutation points, realizes early warning of fill diseases and deformation, and proposes a "four-in-one" anti-subsidence and anti-sliding key technology of high fills in loess areas.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of geological research, in particular to a method for studying the deformation and failure mechanism of high loess fill. BACKGROUND

[0002] At present, "cutting mountains and filling gullies" has become the main way for airport construction in loess mountainous areas. The traditional collapse theory and method cannot meet the new requirements and explain some new phenomena. Some new problems have also appeared in existing high loess fill projects. How to solve the technical problems of high fill projects in loess areas, reduce the settlement, sliding and related diseases of high fill, reduce the construction and operation cost and risk of the whole life cycle of the airport, ensure the safe operation of the airport, reduce carbon emissions, and realize the construction of safe, smart and green airports is a problem that needs to be solved urgently.

[0003] Due to the large difference in elevation of the site in mountainous areas, it often crosses different geological and geomorphological units, and the characteristics of geotechnical engineering are obviously different. There are often adverse geological phenomena. The height of the airport fill is large, and there are factors such as staggered excavation and filling, weak original foundation of filling, significant changes in filling thickness, wide working surface, and large filling amount. Mountainous airports are facing a series of geotechnical and environmental problems that need to be solved.

[0004] 1. Although many high fill airports have been built in China, such as Lvliang Airport with a maximum fill thickness of 127m and Yan'an New Airport with a maximum fill thickness of 120m, engineering problems caused by differential settlement still plague the construction and operation of high fill airports, such as Chengdu Shuangliu Airport, Lijiang Airport, and Jiuhuang Airport. This situation occurs frequently in loess areas, causing serious harm and greatly hindering the rapid development of urban and airport construction and other undertakings.

[0005] 2. Airports have extremely strict requirements for settlement and slope deformation. Once the runway cracks and slips, it will pose a great threat to the takeoff and landing of aircraft. In recent years, global climate change has intensified, and extreme weather conditions have brought greater challenges to the safety of mountainous airport construction and operation. If a mountainous airport that has already been built encounters extreme weather such as the severe rainstorm in Henan in July 2021, a large amount of rainwater will enter the fill body along the uneven settlement cracks in a short period of time, causing the fill body to quickly saturate and reduce its strength, making it extremely easy to cause large-scale collapse of the runway and terminal area, resulting in huge losses.

[0006] 3. The problem of loess-induced settlement and sliding under the action of water-high pressure coupling is still one of the difficult problems in geotechnical engineering. The traditional collapse theory and method cannot meet the new requirements of high fill in mountainous areas, and cannot explain some new phenomena and diseases in high fill projects in mountainous areas. For example, after some high fill projects in the loess area of Northwest China have been completed for 10 years, the settlement and deformation in some areas have not yet stabilized, resulting in diseases such as benching and longitudinal joint widening on the runway pavement in the high fill area.

[0007] 4. Although the airport high fill often uses a more conservative design, however, in the process of filling the valley, the original surface hydrological conditions and groundwater hydrogeological conditions in the valley will be completely changed, and the drainage path of surface water and groundwater will be greatly affected. When there is poor drainage, upper layer of stagnant water or rising groundwater level is formed, and the filler or foundation is prone to wet deformation, so that the deformation of the fill body becomes more complex, and even leads to the instability of the slope. SUMMARY

[0008] (I) Technical problems solved

[0009] In view of the deficiencies of the prior art, the present application provides a loess high fill deformation failure mechanism research method, which uses indoor test, field monitoring and numerical simulation method to explore the whole process of loess area airport high fill deformation failure, according to the principles of soil mechanics, plastic mechanics and variation, proposes a seepage-deformation dynamic coupling theory model of loess water-high pressure coupling subsidence-sliding, reveals the water-high pressure coupling subsidence-sliding mechanism, and proposes a new method for determining the shear strength parameter.

[0010] (II) Technical solutions

[0011] In order to achieve the above object, the present application is realized by the following technical scheme: a loess high fill deformation failure mechanism research method, specifically comprising the following steps:

[0012] S1, a seepage-deformation dynamic coupling theory model of loess water and high pressure coupling subsidence-sliding is proposed;

[0013] S2, the mechanism of loess slope resistance to seepage, water enrichment and pressure rise consistent sliding under the action of water and high pressure is revealed;

[0014] S3, the mechanism of loess foundation resistance to seepage, water enrichment and pressure rise consistent sliding under the action of water and high pressure is revealed;

[0015] S4, a new method for determining the shear strength parameter test in landslide stability evaluation is proposed;

[0016] S5, a variety of InSAR technologies are comprehensively used to obtain mm-level surface deformation data in the study area, three-dimensional surface deformation data are obtained by joint solution, and the post-construction settlement deformation law of the filling body under different filling thickness, filling method and foundation conditions is obtained through analysis;

[0017] S6, based on the combination of GPR and ERT, the disease is identified and its structural characteristics are extracted, and the numerical inversion of airport high fill deformation is used to optimize the design of airport engineering;

[0018] S7, the treatment depth of collapsible loess foundation of airport engineering is optimized;

[0019] S8, propose a high fill "four-in-one" anti-settlement and anti-sliding technology for airports in loess areas, and establish a system design system for airport engineering in loess areas.

[0020] Preferably, a plurality of InSAR technologies are comprehensively used in step S5, including PS-InSAR and SBAS-InSAR.

[0021] Preferably, the seepage deformation dynamic coupling theory model of soil and water coupled with high pressure to cause settlement and sliding in step S1 includes a compaction loess moisture retention model under water and high pressure coupling, a compaction loess moisture infiltration model under water and high pressure coupling, and an elastoplastic constitutive model of compaction loess under water and high pressure coupling.

[0022] Preferably, the shear strength parameter test in the landslide stability evaluation in step S4 includes a constant stress graded immersion test and a constant suction loading test, the constant stress graded immersion test includes an isotropic compression after immersion test, a conventional triaxial shear after immersion test, and an equal stress ratio triaxial compression after immersion test, and the constant suction loading test includes an isotropic compression test, a triaxial shear test, and an equal stress ratio compression test.

[0023] Preferably, the shear strength parameter test in the landslide stability evaluation in step S4 respectively tests the water retention characteristics, the water infiltration characteristics, the deformation characteristics, the yield characteristics, and the critical state characteristics.

[0024] Preferably, the "four-in-one" system of high fill in loess area airport in step S8 includes, in sequence, a fill body base surface, a fill body top surface, a fill body slope surface, a fill and excavation interface, and a fill body.

[0025] Preferably, the intelligent sensing and identification method for settlement and sliding of high fill in loess area airport specifically includes the following steps:

[0026] T1, three-dimensional deformation detection based on time series InSAR technology: obtaining deformation data in the line of sight (LOS direction) and the vertical direction (U direction) of the airport and its surroundings for a long time sequence, and obtaining three-dimensional deformation information to the airport and its surroundings;

[0027] T2, spatiotemporal variation law and early warning of settlement and sliding based on big data mining: studying the spatiotemporal variation law of high fill deformation, and early warning of high fill disease and slope deformation;

[0028] T3, parameter inversion of airport high fill settlement and sliding.

[0029] Preferably, the parameter inversion of airport high fill settlement and sliding in step T3 includes the establishment of a loess airport high fill deformation prediction model and the establishment of a settlement calculation model for a typical high fill.

[0030] (Three) beneficial effects

[0031] The present application provides a loess high fill deformation failure mechanism research method.Compared with the prior art, the loess high fill deformation failure mechanism research method has the following beneficial effects: the loess high fill deformation failure mechanism research method, by utilizing indoor test, field monitoring and numerical simulation method, discusses the whole process of deformation and failure of high fill in loess area airport, according to the principles of soil mechanics, plastic mechanics and variation, puts forward the seepage-deformation dynamic coupling theory model of loess water-high pressure coupling subsidence-sliding, reveals the mechanism of water-high pressure coupling subsidence-sliding, and puts forward a new method for determining shear strength parameters. A variety of InSAR technologies are comprehensively used to obtain large-scale, long-sequence and massive three-dimensional deformation data of high fill in loess area airport, the influence of different factors on deformation is studied by big data deep learning method, the deformation parameters of soil under large load are inversed, the problem of selecting deformation calculation parameters of high fill in airport is solved; the deformation mutation point is identified, and the early warning of fill disease and deformation is realized. On this basis, the "four-in-one" system of high fill in loess area airport is put forward, aiming at different regions, different collapsibility grades and different potential failure forms, neural network, fuzzy optimization and other theories are used to study the prevention and control standards of different elements of "four-in-one", build anti-subsidence and anti-sliding design criteria, and put forward the key technology of anti-subsidence and anti-sliding of high fill in loess area relying on engineering verification feedback, the present application is a summary of the experience of airport construction in collapsible loess area and a new theoretical breakthrough, which has obvious expected benefits, strong market competitiveness, wide application prospect, and can bring considerable economic and social benefits. While reducing the amount of lime and other building materials and the discharge of waste soil, it can indirectly reduce carbon emissions; it is helpful for the optimization and popularization of engineering design in collapsible loess area, ensures the safe operation of airport, reduces the amount of foundation treatment, building materials, energy consumption and construction period, and is expected to save more than 20% of the construction investment in geotechnical engineering for each airport project. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a schematic diagram of the principle of the present application;

[0033] Figure 2 is a schematic diagram of the test research process of the present application;

[0034] Figure 3 is a flow chart of the intelligent identification method of loess area airport high fill settlement and sliding of the present application;

[0035] Figure 4 is a schematic diagram of the volume construction process of the present application. DETAILED DESCRIPTION

[0036] Clearly, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present application.

[0037] Please refer to Figures 1-4 The embodiment of the present application provides a technical scheme: a loess high fill deformation and failure mechanism research method, specifically comprising the following steps:

[0038] S1, a seepage deformation dynamic coupling theory model of loess water and high pressure coupling caused by sinking and sliding is proposed;

[0039] S2, the mechanism of loss slope resistance to seepage, water enrichment and consistent sliding under the action of water and high pressure is disclosed;

[0040] S3, the mechanism of loess foundation resistance to seepage, water enrichment and consistent sliding under the action of water and high pressure is disclosed;

[0041] S4, a new method for determining the shear strength parameter test in landslide stability evaluation is proposed;

[0042] S5, a plurality of InSAR technologies are comprehensively used to obtain mm-level ground surface deformation data in the research area, three-dimensional ground surface deformation data are obtained through joint calculation, and the post-construction settlement deformation law of the filling body under different filling thickness, filling method and foundation conditions is obtained through analysis;

[0043] S6, based on the combination of GPR and ERT, the disease is identified and the structure characteristics are extracted, and the numerical inversion optimization of airport high fill deformation is used to optimize the airport engineering design;

[0044] S7, the treatment depth of collapsible loess foundation of airport engineering is optimized;

[0045] S8, a "four-in-one" anti-sinking and anti-sliding technology for airport high fill in loess area is proposed, and a loess area airport engineering system design system is established.

[0046] In the embodiment of the present application, the plurality of InSAR technologies used in step S5 are PS-InSAR and SBAS-InSAR.

[0047] In the embodiment of the present application, the seepage deformation dynamic coupling theory model of soil water and high pressure coupling caused by sinking and sliding in step S1 includes a compaction loess moisture retention model under the action of water and high pressure coupling, a compaction loess moisture seepage model under the action of water and high pressure coupling, and a compaction loess elastoplastic constitutive model under the action of water and high pressure coupling.

[0048] The shear strength parameter test in the landslide stability evaluation in the step S4 includes a constant stress grading immersion test and a constant suction loading test, the constant stress grading immersion test includes an isotropic compression post-immersion test, a conventional triaxial shear post-immersion test and an equal stress ratio triaxial compression post-immersion test, and the constant suction loading test includes an isotropic compression test, a triaxial shear test and an equal stress ratio compression test, and the shear strength parameter test in the landslide stability evaluation tests the water retention characteristics, the water seepage characteristics, the deformation characteristics, the yield characteristics and the critical state characteristics respectively.

[0049] The step S8 includes a filling body base surface, a filling body top surface, a filling body slope surface, a filling and digging transition surface and a filling body in sequence.

[0050] The intelligent landslide and subsidence identification method for the high fill of the airport in the loess area specifically includes the following steps in the embodiment of the application.

[0051] T1, three-dimensional deformation detection based on time series InSAR technology: obtaining long time series deformation data of the airport and its surrounding in the line of sight (LOS direction) and the vertical direction (U direction), and obtaining three-dimensional deformation information of the airport and its surrounding;

[0052] T2, spatio-temporal variation law and early warning of subsidence and landslide based on big data mining: studying the spatio-temporal variation law of the high fill deformation, and early warning the high fill diseases and the slope deformation;

[0053] T3, parameter inversion of the subsidence and landslide of the high fill of the airport: the parameter inversion of the subsidence and landslide of the high fill of the airport includes establishing a deformation prediction model of the high fill of the loess airport and establishing a subsidence calculation model of the typical high fill.

[0054] In summary, the present application uses indoor tests, field monitoring and numerical simulation methods to explore the whole process of deformation and failure of high fill in loess area of airport, proposes a seepage-deformation dynamic coupling theory model of water-high pressure coupling caused by subsidence and sliding in loess, reveals the mechanism of water-high pressure coupling caused by subsidence and sliding, and proposes a new method for determining shear strength parameters. A variety of InSAR technologies are comprehensively used to obtain large-scale, long-sequence and massive three-dimensional deformation data of high fill in loess area of airport, the influence law of different factors on deformation is studied by big data deep learning method, the deformation parameters of soil under large load are inversed, the problem of selecting deformation calculation parameters of high fill in airport is solved, and the deformation mutation point is identified to realize early warning of fill disease and deformation. On this basis, the "four-in-one" system of high fill in loess area of airport is proposed, the neural network, fuzzy optimization and other theories are used to study the prevention and control standards of different elements of "four-in-one", the anti-subsidence and anti-sliding design criteria are constructed, and the key technologies of anti-subsidence and anti-sliding of high fill in loess area are proposed relying on engineering verification feedback. The present application is a summary of the experience of airport construction in collapsible loess area and a new theoretical breakthrough, and has obvious expected benefits, strong market competitiveness and wide application prospect, which can bring considerable economic and social benefits. While reducing the amount of construction materials such as lime and the discharge of spoil, it can indirectly reduce carbon emissions; it is helpful for the optimization and popularization of engineering design in collapsible loess area, ensures the safe operation of airport, reduces the amount of foundation treatment, the amount of construction materials, energy consumption and construction period, and is expected to save more than 20% of the construction investment in geotechnical engineering for each airport project.

[0055] Meanwhile, the contents not described in detail in the present specification are all the prior art known to those skilled in the art.

[0056] It should be noted that, in the present text, relational terms such as first and second and the like can only be used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising" or any other variant thereof are intended to cover non-exclusive inclusions, so that a process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such a process, method, article or equipment.

[0057] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for studying the deformation and failure mechanism of high loess embankments, characterized in that: Specifically comprising the following steps: S1, propose a seepage deformation dynamic coupling theory model of loess water and high pressure coupling causing sinking and sliding; S2, reveal the mechanism of loess slope resistance to seepage, water enrichment and pressure rise consistent sliding under the action of water high pressure; S3, reveal the mechanism of loess foundation resistance to seepage, water enrichment and pressure rise consistent sliding under the action of water high pressure; S4, propose a new method for determining shear strength parameters in landslide stability evaluation; S5, comprehensively use multiple InSAR technologies to obtain mm-level ground surface deformation data in the study area, obtain three-dimensional ground surface deformation data through joint solution, and obtain the deformation law of filling body post-construction settlement under different filling thickness, filling method and foundation conditions through analysis; S6, identify and extract the structural characteristics of the disease based on the combination of GPR and ERT, and optimize the airport engineering design through numerical inversion of airport high fill deformation; S7, optimize the treatment depth of collapsible loess foundation of airport engineering; S8, propose a "four-in-one" anti-sinking and anti-sliding technology for high fill of airport in loess area, and establish a system design system for airport engineering in loess area. The "four-in-one" system of high fill of airport in loess area includes filling body bottom surface, filling body top surface, filling body slope surface, filling and excavation interface and filling body in turn.

2. The method for studying the deformation and failure mechanism of high loess fill according to claim 1, characterized in that: The multiple InSAR technologies used in step S5 are PS-InSAR and SBAS-InSAR.

3. The method for studying the deformation and failure mechanism of high loess fill according to claim 1, characterized in that: The seepage deformation dynamic coupling theory model of soil water and high pressure coupling causing sinking and sliding in step S1 includes a compaction loess moisture retention model under the action of water high pressure coupling, a compaction loess moisture seepage model under the action of water high pressure coupling, and a compaction loess elastic-plastic constitutive model under the action of water high pressure coupling.

4. The method for studying the deformation and failure mechanism of high loess fill according to claim 1, characterized in that: The shear strength parameter test in landslide stability evaluation in step S4 includes constant stress graded immersion test and constant suction loading test. The constant stress graded immersion test includes isotropic compression after immersion test, conventional triaxial shear after immersion test and equal stress ratio triaxial compression after immersion test, and the constant suction loading test includes isotropic compression test, triaxial shear test and equal stress ratio compression test.

5. The method for studying the deformation and failure mechanism of high loess fill according to claim 4, characterized in that: The shear strength parameter test in landslide stability evaluation in step S4 respectively tests the water retention characteristics, water seepage characteristics, deformation characteristics, yield characteristics and critical state characteristics.

6. The method for studying the deformation and failure mechanism of high loess fill according to claim 1, characterized in that: The intelligent sensing identification method for settlement and sliding of high fill of airport in loess area specifically comprises the following steps: T1, three-dimensional deformation detection based on time series InSAR technology: obtaining long time series deformation data in line of sight and vertical direction of airport and its surrounding area, and obtaining three-dimensional deformation information of airport and its surrounding area; T2, spatiotemporal variation law of settlement and sliding and early warning based on big data mining: studying the spatiotemporal variation law of high fill deformation, and early warning of high fill disease and slope deformation; T3, parameter inversion of settlement and sliding of airport high fill.

7. The method for studying the deformation and failure mechanism of high loess fill according to claim 6, characterized in that: The parameter inversion of settlement and sliding of airport high fill in step T3 includes establishment of loess airport high fill deformation prediction model and establishment of settlement calculation model of typical high fill.

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