Prediction method for loess high fill humidifying settlement induced by pipeline water seepage

Abstract

The invention belongs to the technical field of geological research, and particularly discloses a method for predicting loess high fill humidifying settlement induced by pipeline water seepage, which comprises the following steps of: S1, obtaining a humidifying characteristic parameter interpolation function of a filling body under different compaction degrees and different water contents; s2, through Comsol finite element software, the interpolation function is embedded into the soil body elastic-plastic constitutive model, the change process of a moisture field, a stress field and a displacement field of a high-fill foundation filling body is simulated, and the humidifying settlement change rule under different pipeline leakage working conditions is obtained; and S3, the ratio of the radius of the maximum infiltration circle area to the radius of the drainage pipeline is defined as the relative saturation diameter, and the relative saturation diameter is used for describing the loess high fill humidifying influence range caused by pipeline leakage. By the adoption of the method for predicting loess high-fill humidifying settlement induced by pipeline water seepage, the prediction and coping capacity of a loess high-fill foundation project is improved, the pipeline water seepage problem of the high-fill foundation project is monitored in real time, and smooth safety maintenance work of a drainage pipeline is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of geological research, and in particular to a method for predicting wetting and settlement of loess high fill induced by pipeline water seepage. Background Art

[0002] High fill construction projects in Northwest my country and other places have shown a sustained and vigorous development momentum, and the demand for land resources is increasing day by day. High fill foundation engineering has become a commonly used engineering method in various engineering practices. However, the loess high fill foundations in these areas are mostly soft and collapsible loess, with loose soil structure and strong collapsibility. This special geological feature makes it very easy for high fill foundations to suffer from disasters such as wetting, deformation and settlement when facing changes in hydrological factors such as rainfall, drainage pipe leakage and drainage blind ditch failure. In addition, the wetting, deformation and settlement laws of high fill foundations are also affected by a combination of factors such as foundation material characteristics, water infiltration, fill structure, foundation reinforcement and treatment.

[0003] In the prior art, in view of the current situation of wetting and settlement of high fill foundation, Ge Miaomiao et al. took loess high fill foundation soil as the research object, and conducted compression, wetting-dehumidification tests and micro-structure research on compacted loess, and studied the vertical stress and wetting deformation laws under constant moisture content compression and constant vertical stress wetting conditions from both microscopic and macroscopic aspects. In view of the current situation of pipeline leakage on high fill wetting and settlement, Dai ZL et al. studied the influence of groundwater level, soil parameters, pipeline burial depth and other factors on ground collapse through seepage theory, indoor model tests, numerical simulation and other methods, and then revealed the mechanism of ground collapse induced by seepage of underground drainage pipelines. However, it ignores the mutual effects of pipeline seepage and other factors, and still cannot solve the problem that it is difficult to accurately predict the wetting deformation of loess high fill foundation under the influence of changes in pipeline seepage conditions. Summary of the invention

[0004] The purpose of the present invention is to provide a method for predicting wetting and settlement of loess high fill induced by pipeline seepage, to systematically predict wetting and settlement of loess high fill foundation due to drainage pipeline seepage, to improve the prediction and response capabilities of loess high fill foundation engineering, to monitor pipeline seepage problems in high fill foundation engineering in real time, and to facilitate the smooth implementation of safe maintenance work of drainage pipelines.

[0005] To achieve the above object, the present invention provides a method for predicting wetting settlement of loess high fill induced by pipeline water seepage, comprising the following steps:

[0006] S1. Transforming the fitting function of the mechanical characteristic parameters of the fill body under different compaction degrees as the moisture content changes, and obtaining the interpolation function of the wetting characteristic parameters of the fill body under different compaction degrees and different moisture contents;

[0007] S2. By using Comsol finite element software, the interpolation function is embedded into the elastic-plastic constitutive model of the soil, and the change process of the moisture field, stress field and displacement field of the high fill foundation in the initial state, seepage state and stable state is simulated to obtain the change law of humidification settlement under different pipeline leakage conditions;

[0008] S3. Define the ratio of the radius of the maximum infiltration circle area to the radius of the drainage pipe as the relative saturated diameter, which is used to describe the influence range of loess high fill wetting caused by pipe leakage. The influence range of high fill foundation wetting and the change process of wetting settlement are predicted by the relative saturated diameter, the maximum infiltration circle area and the drainage pipe leakage time.

[0009] S4. Predict the wetting and settlement change process of high fill foundation based on the leakage location and number of leakage points in the drainage pipe.

[0010] Preferably, in S1, the value range of the compaction degree λ is 0.80 to 0.99.

[0011] Preferably, in S1, the pipeline leakage condition includes the drainage pipeline leakage time, the drainage pipeline leakage position, the number of drainage pipeline leakage points, the water pressure in the drainage pipeline, the drainage pipeline diameter and the drainage pipeline buried depth, and the drainage pipeline leakage position includes the arch crown V, the left arch shoulder Sp11, the left arch waist S1, the left arch foot Sp12, the arch bottom Bp, the right arch foot Sp r2 , right arch waist Sr, right arch span Spr1 and full-section leakage All. The number of leakage points in the drainage pipe is 1, 2, 3, 4, 5, 6, 7, 8 or full leakage.

[0012] Preferably, in S1, the interpolation function of the wetting characteristic parameter of the fill body at different compaction degrees or different moisture contents is specifically:

[0013] Elastic modulus E, cohesion c, internal friction angle of fill body under different compaction degree λ and different water content w Interpolation function of the wetting characteristic parameters of four fill bodies such as bulk density γ.

[0014] Preferably, in S2, the grids of the high fill soil within the leakage and humidification settlement range of the drainage pipe are densified, and the grids of the high fill soil outside the leakage and humidification settlement range of the drainage pipe are sparsely processed, the initial state is that there is no water seepage in the drainage pipe, the seepage state is that the water inside the drainage pipe begins to seep out after the drainage pipe is damaged and continues to seep for a period of time, and the stable state is that the water pressure in the drainage pipe is balanced with the water pressure of the external water in the soil, and no more seepage occurs;

[0015] The difference between the displacement field S2 in the stable state and the displacement field S0 in the initial state is the humidification deformation △S. The maximum humidification deformation is set to △S, and the maximum infiltration circle area is A. max.

[0016] Preferably, S2 comprises the following steps:

[0017] S21. Analysis of initial displacement field and initial moisture field:

[0018] The study was set as a steady-state study, the pressure head boundary condition in the Richards equation module was disabled, the soil elastic-plastic constitutive model was divided into equivalent units using the Comsol finite element software, and the initial moisture field w0, initial stress field σ0, and initial displacement field S0 in the fill were obtained by setting the initial state;

[0019] S22. Analysis of displacement field under the influence of drainage pipe infiltration:

[0020] Set the total time of drainage pipe leakage and the output time step, enable the pressure head boundary condition, set the dependent variable to the initial state water field w0, initial stress field σ0 and initial displacement field S0 as the initial value of the seepage state for analysis, and calculate the moisture field w1, stress field σ1 and displacement field S1 of the high fill foundation after humidification in the soil under different compaction degrees and different pipe leakage conditions through the seepage module;

[0021] S23. Analysis of displacement field after seepage stabilization in drainage pipes:

[0022] The total time and output time step of the settlement stabilization process are set, and the pressure head boundary condition is disabled. The dependent variables are set to the moisture field w1, stress field σ1, and the last solution of the displacement field S1 is set to the initial value of the stable state for analysis. The surface settlement stabilization process of loess high fill after infiltration of the drainage pipe is simulated. The moisture field w2, stress field σ2, and displacement field S2 in the soil body of the high fill foundation are calculated through the seepage module after the moisture in the drainage pipe no longer seeps out.

[0023] Preferably, in S2, based on numerical analysis, the variation law of humidification and sedimentation under different pipeline leakage conditions is obtained, including:

[0024] Variations of moisture and displacement fields in high fill foundations at different pipeline leakage locations;

[0025] Variations of moisture and displacement fields in high fill foundations under different numbers of pipeline leakage points;

[0026] Variations of water and displacement fields in high fill foundation under different water pressures in pipes;

[0027] Variation of moisture and displacement fields in high fill foundation under different pipeline diameters;

[0028] Variations of moisture and displacement fields in high fill foundations at different pipeline burial depths;

[0029] Variation of moisture and displacement fields in high fill foundation under different fill compaction degrees.

[0030] Therefore, the present invention adopts the above-mentioned pipeline seepage-induced loess high fill humidification settlement prediction method, and the beneficial effects are as follows:

[0031] (1) The present invention proposes a simulation method for the influence of factors such as drainage pipe leakage position, number of drainage pipe leakage points, water pressure in drainage pipe, drainage pipe diameter, drainage pipe burial depth, and fill compaction degree on the moistening of loess high fill through the damage function of fill body with increasing water content under moistening conditions at different compaction degrees.

[0032] (2) Based on numerical analysis, the present invention obtains prediction formulas for relative saturation diameter, maximum infiltration circle area, and pipeline leakage stabilization time, and describes the wetting and sedimentation of loess high fill caused by shallow pipeline leakage, thereby improving the prediction and response capabilities of loess high fill foundation engineering, monitoring pipeline seepage problems in high fill foundation engineering in real time, and facilitating the smooth implementation of safe maintenance work on drainage pipelines.

[0033] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The model and calculation result diagram of different drainage pipe leakage positions of a method for predicting wetted settlement of loess high fill induced by pipe seepage in the present invention, wherein (a) is P i =V; (b) is P i =Bp; (c) is P i =S l ; (d) is P i = Sp11; (e) is P i =Spl2;

[0035] Figure 2 It is a diagram showing the variation regularity of the infiltration zone area according to an embodiment of a method for predicting the wetting and settlement of loess high fill induced by pipeline water seepage of the present invention;

[0036] Figure 3 It is a relative saturated diameter variation law diagram of an embodiment of a method for predicting wetting and settling of loess high fill induced by pipeline water seepage of the present invention;

[0037] Figure 4 It is a graph showing the variation regularity of the maximum surface settlement in an embodiment of a method for predicting the wetting settlement of loess high fill induced by pipeline water seepage of the present invention;

[0038] Figure 5 It is a diagram showing the variation regularity of leakage stability time in an embodiment of a method for predicting wetting and settling of loess high fill induced by pipeline water seepage of the present invention. DETAILED DESCRIPTION

[0039] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0040] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0041] Embodiment 1

[0042] A method for predicting wetting settlement of loess high fill induced by pipeline water seepage comprises the following steps:

[0043] The value range of S1 and compaction degree λ is 0.80-0.99 (the values ​​are 0.88, 0.90, 0.93, 0.95, and 0.98). The fitting function of the mechanical characteristic parameters of the fill body under different compaction degrees as the moisture content changes is transformed to obtain the interpolation function of the wetting characteristic parameters of the fill body under different compaction degrees and different moisture contents.

[0044] Specifically, the pipeline leakage conditions include the drainage pipeline leakage time, the drainage pipeline leakage location, the number of drainage pipeline leakage points, the water pressure in the drainage pipeline, the drainage pipeline diameter and the drainage pipeline burial depth.

[0045] (1) The drainage pipe leakage lasts for 10 days, 20 days, 30 days, 40 days and 50 days.

[0046] (2) The leakage locations of the drainage pipe include the arch crown V, left arch shoulder Spl1, left arch waist Sl, left arch foot Spl2, arch bottom Bp, right arch foot Sp r2 , right arch waist Sr, right arch span Spr1 and full section leakage Al.

[0047] (3) The number of leakage points in the drainage pipe is 1, 2, 3, 4, 5, 6, 7, 8 or all leakage.

[0048] (4) The water pressure in the drainage pipe is 0.1, 0.15, 0.2, 0.25, and 0.3, in MPa.

[0049] (5) The diameters of drainage pipes are 0.2, 0.3, 0.4, 0.5, 0.6, and 0.75, in meters.

[0050] (6) The buried depth of drainage pipes is 0.3, 0.5, 0.7, 1.0, 1.2, and 1.4, in meters.

[0051] The numerical scheme of the interpolation function of the wetting characteristic parameters of the fill body under different compaction degrees or different moisture contents is specifically shown in Table 1, and then the model and calculation result diagram of the leakage position of different drainage pipes are obtained, as shown in Figure 1 As shown in the figure, S eis the effective saturation, A is the area of ​​the infiltration zone, and after the pipeline leakage reaches stability, the area enclosed by the saturated area of ​​the compacted soil around the pipeline is called the maximum infiltration zone area A max ; S max is the maximum surface settlement. Due to the uneven wetting and settlement of the surface caused by pipeline leakage, the maximum settlement is called S max .

[0052] Table 1 Numerical scheme

[0053] Numerical scheme name Variable factors Solution 1 <![CDATA[Leakage location P i > <![CDATA[V、Spr1、Sr、Sp r2 、Bp、Spl2、Sl、Spl1、All]]> Solution 2 Number of leakage points n 1, 2, 3, 4, 5, 6, 7, 8, full leakage Option 3 <![CDATA[Internal water pressure P m , MPa,]]> 0.1、0.15、0.2、0.25、0.3 Option 4 Pipe diameter d, m 0.2、0.3、0.4、0.5、0.6、0.75 Option 5 Buried depth h, m 0.3、0.5、0.7、1.0、1.2、1.4 Option 6 Soil compaction degree λ 0.88、0.90、0.93、0.95、0.98

[0054] S2. Through Comsol finite element software, the interpolation function is embedded into the elastic-plastic constitutive model of the soil to simulate the change process of the moisture field, stress field and displacement field of the high fill foundation fill in the initial state, seepage state and stable state, and the change law of humidification settlement under different pipeline leakage conditions is obtained.

[0055] Specifically, the variation rules of water field and displacement field of high fill foundation under different pipeline leakage positions are as follows:

[0056] Under different pipeline leakage conditions, the leakage lasts for 10 days, 20 days, 30 days, 40 days, and 50 days respectively. After reaching the maximum seepage and wetting influence depth, the change law of the infiltration circle area A inside the fill body is as follows: Figure 2 As shown in the figure. Under different pipeline leakage conditions, the size of the final infiltration circle area A in the foundation is from large to small: full leakage All> right arch waist Sr> arch crown V> left arch waist Sl> arch bottom Bp> right arch foot Spr2> left arch shoulder Spl1> right arch shoulder Spr1> left arch foot Spl2. After 30 days of pipeline infiltration, when the pipeline is fully leaking, the maximum A in the foundation is 1.27m 2 When the right spandrel of the pipeline leaks, A is at least 0.08m 2 When the pipeline is completely leaking, A grows fastest and the final wetted area is the largest. The growth rate of A at the right haunch and crown of the pipeline is faster than that at other single leaking locations, and the final A is larger. The leakage rate and the final A of the wetted area at the left haunch, arch bottom, right arch foot, left arch spandrel, left arch foot, and right arch spandrel are not much different.

[0057] The variation law of the relative saturated diameter η inside the fill body is as follows: Figure 3 As shown in the figure. Under different pipeline leakage conditions, the relative saturation diameter η in the foundation is from large to small: full leakage All> right arch waist Sr> arch crown V> left arch waist Sl> arch bottom Bp> right arch foot Spr2> left arch span Spl1> right arch span Spr1> left arch foot Spl2. After 30 days of pipeline infiltration, when the pipeline leakage position is full leakage, the maximum η in the foundation is 2.12, and when the pipeline leakage position is the left arch foot, the minimum η in the foundation is 0.54.

[0058] Maximum surface settlement S max The changing rules are as follows Figure 4 Under different pipeline leakage conditions, the maximum surface settlement when the pipeline is completely leaking is much greater than that at other pipeline leakage locations. max The size of the pipeline is from large to small: full leakage All> right arch waist Sr> left arch waist Sl> arch crown V> right arch shoulder Spr1> left arch shoulder Spl1> right arch foot Spr2> left arch foot Spl2> arch bottom Bp. After 30 days of pipeline infiltration, when the pipeline leakage position is full leakage, S max The maximum is -2.14mm. When the pipeline leakage position is the arch bottom, S max The minimum is -0.04mm.

[0059] After the seepage in the high fill foundation reaches stability under different pipeline leakage positions, the corresponding time is the seepage stabilization time t2 of the pipeline leakage in the fill body, and its changing law is as follows: Figure 5 As shown. Under different pipeline leakage positions, the leakage stabilization time when the pipeline is fully leaking is much longer than other pipeline leakage positions. The size of the pipeline leakage stabilization time t2 is from large to small: full leakage All> arch bottom Bp> left arch waist Sl> right arch waist Sr> arch top V> right arch shoulder Spr1> left arch foot Spr2> left arch shoulder Spl1> right arch foot Spr2; the leakage stabilization time of the arch shoulders and arch feet on both sides of the pipeline is not much different. When the pipeline infiltration is stable, when the pipeline leakage position is full leakage, t2 is the longest at 25 days, and when the pipeline leakage position is the right arch foot, t2 is the shortest at 1.4 days.

[0060] S3. Define the ratio of the radius of the maximum infiltration circle area to the radius of the drainage pipe d / 2 as the relative saturation diameter η, which is used to describe the influence range of loess high fill humidification caused by pipeline leakage. The expression is as follows:

[0061]

[0062] The influence range of high fill foundation humidification and the change process of humidification settlement are predicted by relative saturated diameter, maximum infiltration circle area and drainage pipe leakage time.

[0063] S4. Predict the wetting and settlement change process of high fill foundation based on the leakage location and number of leakage points in the drainage pipe.

[0064] Similarly, the variation rules of water field and displacement field of high fill foundation under different numbers of pipeline leakage points are as follows:

[0065] Under different conditions of the number of pipeline leakage points, the growth rate of A in the foundation when the pipeline is completely leaking is faster than the growth rate of A in the foundation when other leakage points are leaking. When there are 1-8 leakage points, the growth rate of A in the foundation is not much different. The final A reached in the foundation is linearly related to the number of leakage points. The more the number of pipeline leakage points, the larger the final infiltration circle area that can be reached in the foundation.

[0066] Under different working conditions of pipeline leakage points, the size of the relative saturated diameter η in the foundation is linearly related to the number of leakage points. The more the number of pipeline leakage points, the larger the relative saturated diameter in the foundation.

[0067] Under different conditions of pipeline leakage points, the maximum surface settlement when the pipeline is completely leaking is much greater than the number of other pipeline leakage points. The size of the maximum surface settlement is linearly related to the number of leakage points. The more the number of pipeline leakage points, the greater the maximum surface settlement.

[0068] Under different working conditions of pipeline leakage points, the size of pipeline leakage stabilization time t2 is linearly related to the number of pipeline leakage points. The more the number of pipeline leakage points, the longer the pipeline leakage stabilization time.

[0069] Similarly, the variation rules of water field and displacement field of high fill foundation under different water pressures in pipelines are as follows:

[0070] Under different water pressure conditions in the pipeline, when the compaction degree is 0.1-0.2MPa, since the water pressure in the pipeline is lower than the water pressure outside the soil outside the pipeline, the water in the pipeline cannot infiltrate into the surrounding soil in the early stage, and A in the foundation does not change. After a period of water accumulation in the pipeline, the water in the pipeline begins to infiltrate into the surrounding soil, and the infiltration circle area A begins to change. When the compaction degree is 0.25-0.3MPa, the water pressure in the pipeline is large enough, and the water in the pipeline can directly infiltrate into the surrounding soil. After 50 days of pipeline infiltration, when the water pressure in the pipeline is 0.3MPa, the maximum A in the foundation is 1.34m 2 When the water pressure in the pipe is 0.1 MPa, the minimum value of A is 0.26 m 2 .

[0071] There is a linear relationship between the water pressure in the pipe and the growth rate of the wetted circle area in the foundation. The greater the water pressure in the pipe, the faster the growth rate of the wetted circle area in the foundation. There is also an approximately linear relationship between the water pressure in the pipe and the final area of ​​the wetted circle in the foundation. The greater the water pressure in the pipe, the larger the final wetted circle area that can be achieved in the foundation.

[0072] Under different water pressure conditions in the pipeline, the water pressure in the pipeline is linearly related to the relative saturated diameter η. The greater the water pressure in the pipeline, the larger the relative saturated diameter in the foundation.

[0073] Under different pipeline water pressure conditions, the pipeline water pressure and the maximum surface settlement are approximately linearly related. The greater the pipeline water pressure, the greater the maximum surface settlement. After the pipeline has infiltrated for 50 days, when the pipeline water pressure is 0.3 MPa, S max The maximum is -2.14mm. When the water pressure in the pipe is 0.1MPa, S max The minimum is -0.93mm.

[0074] Under different water pressure conditions in the pipeline, the pipeline leakage stabilization time t2 includes the initial time t2 when the leakage condition is reached. 2a and the time t after the seepage reaches stability 2b The size of the pipeline leakage stabilization time is approximately linearly related to the water pressure in the pipeline. The greater the water pressure in the pipeline, the longer the pipeline leakage seepage time; the greater the water pressure in the pipeline, the shorter the pipeline leakage accumulation time. When the water pressure in the pipeline P m When the water pressure is ≥0.25MPa, the leakage accumulation time is 0 days. When the pipeline infiltration is stable, when the water pressure in the pipeline is 0.1MPa, the longest pipeline leakage accumulation time is 24 days, and the shortest pipeline leakage seepage time is 6 days; when the water pressure in the pipeline is 0.3MPa, the shortest leakage stabilization time is 0 days, and the longest pipeline leakage seepage time is 26 days.

[0075] Similarly, the variation rules of water field and displacement field of high fill foundation under different pipeline diameters are as follows:

[0076] Under different pipeline diameter conditions, the growth rate of the pipeline diameter and the infiltration area S in the foundation is linearly related. The larger the pipeline diameter, the faster the growth rate of the infiltration area in the foundation. The pipeline diameter and the final area of ​​the infiltration area in the foundation are also approximately linearly related. The larger the pipeline diameter, the larger the final infiltration area that can be achieved in the foundation. After 50 days of pipeline infiltration, when the pipeline diameter is 0.75m, the maximum A in the foundation is 3.97m 2 When the pipe diameter is 0.2m, the minimum A is 0.39m 2 .

[0077] Under different pipeline diameter conditions, the pipeline diameter and the relative saturation diameter η in the foundation are approximately linearly related. When the pipeline diameter d≦0.4m, η increases with the increase of the pipeline diameter; when the pipeline diameter d≧0.4m, η decreases with the increase of the pipeline diameter. After 50 days of pipeline infiltration, when the pipeline diameter is 0.4m, η in the foundation reaches a maximum value of 2.33, and when the pipeline diameter is 0.75m, η is a minimum of 1.47.

[0078] Under different pipeline diameter conditions, the pipeline diameter and the maximum surface settlement are approximately linearly related. The larger the pipeline diameter, the greater the maximum surface settlement. After 50 days of pipeline infiltration, when the pipeline diameter is 0.75m, S maxThe maximum is -8.71mm, when the pipe diameter is 0.2m, S max The minimum is -0.48mm.

[0079] Under different pipeline diameter conditions, the pipeline leakage stabilization time t2 is basically the same. When the pipeline diameter is 0.2, t2 is the largest, which is 27.5 days. When the pipeline diameter is 0.3, 0.4, 0.5, 0.6, and 0.75, t2 remains unchanged at 27 days. At this time, the pipeline diameter has little effect on the pipeline infiltration stabilization time.

[0080] Similarly, the variation rules of water field and displacement field of high fill foundation under different pipeline burial depths are as follows:

[0081] Under different pipeline burial depth conditions, the growth rate of the infiltration zone area in the foundation is linearly related to the pipeline burial depth. The smaller the pipeline burial depth, the smaller the overlying soil pressure, the easier it is for the water in the pipeline to infiltrate into the surrounding soil, and the faster the growth rate of the infiltration zone area in the foundation. The final infiltration zone area A in the foundation reaches its maximum at 0.7m. Due to different conditions such as the thickness of the overlying soil layer on the pipeline and the water pressure outside the pipeline, the final infiltration zone area that can be achieved at different pipeline burial depths is also different. After 50 days of pipeline infiltration, when the pipeline burial depth is 0.7m, the maximum infiltration zone area in the foundation is 1.58m 2 When the pipe diameter is 0.3m, the minimum wetted area is 0.84m 2 .

[0082] Under different pipeline burial depth conditions, the relative saturated diameter η in the foundation increases with the increase of pipeline burial depth, reaches the maximum value when the burial depth h = 0.7m, and then decreases with the increase of pipeline burial depth. After 50 days of pipeline infiltration, the maximum relative saturated diameter in the foundation is 2.34 when the pipeline burial depth is 0.7m, and the minimum relative saturated diameter is 1.65 when the pipeline diameter is 1.4m. This is because when the pipeline is buried shallowly, the water leaked from the pipeline infiltrates into the ground and even accumulates water on the surface, resulting in a smaller actual infiltration circle area. Under the same pipeline diameter, the relative saturated diameter continues to increase; subsequently, as the pipeline burial depth increases, the pressure of the overburden on the pipeline increases, and the water in the pipeline is difficult to infiltrate into the surrounding soil, the infiltration circle area decreases, and under the same pipeline diameter, the relative saturated diameter continues to decrease.

[0083] Under different pipeline burial depth conditions, when the pipeline burial depth h≦0.7m, the maximum surface settlement S max The size of S increases with the increase of pipeline burial depth; when the pipeline burial depth h≧0.7m, the size of the maximum surface settlement decreases with the increase of pipeline burial depth; when the pipeline burial depth h≧1.0m, the maximum surface settlement remains basically unchanged. After 50 days of pipeline infiltration, when the pipeline burial depth is 0.7m, S max The maximum is -2.44mm, when the pipe diameter is 0.3m, Smax The minimum is -1.41mm.

[0084] Under different pipeline burial depth conditions, the pipeline infiltration stabilization time t2 is approximately linearly related to the pipeline burial depth. The greater the pipeline burial depth, the longer the pipeline infiltration stabilization time, and the growth rate of the pipeline infiltration stabilization time gradually decreases with the increase of the pipeline burial depth. When the pipeline burial depth is 0.3m, the pipeline infiltration stabilization time is the shortest 5 days; when the pipeline burial depth is 1.4m, the pipeline infiltration stabilization time is the longest 18 days.

[0085] Similarly, the variation rules of moisture field and displacement field of high fill foundation under different fill compaction degrees are as follows:

[0086] Under the same pipeline leakage type and different fill compaction conditions, the fill compaction and the growth rate of the infiltration circle area in the foundation are approximately linearly related. The greater the fill compaction, the slower the growth rate of the infiltration circle area A in the foundation. The fill compaction and the final area of ​​the infiltration circle in the foundation are also approximately linearly related. The greater the fill compaction, the smaller the final infiltration circle area A that can be achieved in the foundation. After 50 days of pipeline infiltration, when the fill compaction is 0.88, the maximum A is 4.53m 2 When the compaction degree of fill is 0.98, the minimum value of A is 4.02m 2 .

[0087] Under the same pipeline leakage type and different fill compaction conditions, the fill compaction and the relative saturated diameter η in the foundation are approximately linearly related. The greater the fill compaction, the smaller the relative saturated diameter in the foundation. After 50 days of pipeline infiltration, when the fill compaction is 0.88, the maximum η in the foundation is 1.6, and when the fill compaction is 0.98, the minimum η is 1.51.

[0088] Under the same pipeline leakage type and different fill compaction conditions, the fill compaction degree and the maximum surface settlement S max It is approximately a linear relationship. The greater the compaction degree of the fill, the smaller the maximum surface settlement. After 50 days of pipe infiltration, when the compaction degree of the fill is 0.88, S max The maximum is -12.96mm. When the compaction degree of fill is 0.98, S max The minimum is -4.76mm.

[0089] Under the same pipeline leakage type and different fill compaction conditions, the fill compaction and pipeline infiltration stabilization time t2 are approximately linearly related. The greater the fill compaction, the shorter the pipeline infiltration stabilization time. When the fill compaction is 0.88, t2 is the longest at 30 days, and when the fill compaction is 0.98, t2 is the shortest at 17 days.

[0090] Therefore, the present invention adopts the above-mentioned pipeline seepage induced loess high fill wetting and settlement prediction method, and conducts systematic wetting and settlement prediction on loess high fill foundation due to drainage pipeline seepage, thereby improving the prediction and response capabilities of loess high fill foundation engineering, monitoring the pipeline seepage problem of high fill foundation engineering in real time, and facilitating the smooth implementation of safe maintenance work of drainage pipelines.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for predicting wetting and sedimentation of loess high fill induced by pipeline seepage, characterized in that: The following steps are involved: S1. Transforming the fitting function of the mechanical characteristic parameters of the fill body under different compaction degrees as the moisture content changes, and obtaining the interpolation function of the wetting characteristic parameters of the fill body under different compaction degrees and different moisture contents; S2. By using Comsol finite element software, the interpolation function is embedded into the elastic-plastic constitutive model of the soil, and the change process of the moisture field, stress field and displacement field of the high fill foundation in the initial state, seepage state and stable state is simulated to obtain the change law of humidification settlement under different pipeline leakage conditions; S3. Define the ratio of the radius of the maximum infiltration circle area to the radius of the drainage pipe as the relative saturated diameter, which is used to describe the influence range of loess high fill wetting caused by pipe leakage. The influence range of high fill foundation wetting and the change process of wetting settlement are predicted by the relative saturated diameter, the maximum infiltration circle area and the drainage pipe leakage time. S4. Predict the wetting and settlement change process of high fill foundation based on the leakage location and number of leakage points in the drainage pipe.

2. The method for predicting wetting settlement of loess high fill induced by pipeline water seepage according to claim 1 is characterized in that: In S1, the compaction degree λ ranges from 0.80 to 0.

99.

3. The method for predicting wetting settlement of loess high fill induced by pipeline water seepage according to claim 2 is characterized in that: In S1, the pipeline leakage conditions include the drainage pipeline leakage time, drainage pipeline leakage location, the number of drainage pipeline leakage points, the water pressure in the drainage pipeline, the drainage pipeline diameter and the drainage pipeline buried depth. The drainage pipeline leakage locations include the arch crown V, the left arch shoulder Spl1, the left arch waist Sl, the left arch foot Spl2, the arch bottom Bp, the right arch foot Sp r2 , right arch waist Sr, right arch span Spr1 and full-section leakage All. The number of leakage points in the drainage pipe is 1, 2, 3, 4, 5, 6, 7, 8 or full leakage.

4. A method for predicting wetting and settling of loess high fill induced by pipeline water seepage according to claim 3, characterized in that: In S1, the interpolation function of the wetting characteristic parameter of the fill body under different compaction degrees or different moisture contents is specifically: Interpolation functions of the wetting characteristic parameters of four fill bodies, namely, elastic modulus E, cohesion c, internal friction angle φ, and bulk density γ, under different compaction degrees λ and different moisture contents w.

5. The method for predicting wetting settlement of loess high fill induced by pipeline water seepage according to claim 1 is characterized in that: In S2, the grids of the high fill soil within the leakage and humidification settlement range of the drainage pipe are densified, and the grids of the high fill soil outside the leakage and humidification settlement range of the drainage pipe are sparsely processed. The initial state is that there is no water seepage in the drainage pipe, the seepage state is that the water inside the drainage pipe begins to seep out after the drainage pipe is damaged and continues to seep for a period of time, and the stable state is that the water pressure in the drainage pipe is balanced with the water pressure of the external water in the soil, and no more seepage occurs; The difference between the displacement field S2 in the stable state and the displacement field S0 in the initial state is the humidification deformation △S. The maximum humidification deformation is set to △S, and the maximum infiltration circle area is A. max .

6. A method for predicting wetting settlement of loess high fill induced by pipeline water seepage according to claim 5, characterized in that: S2 includes the following steps: S21. Analysis of initial displacement field and initial moisture field: The study was set as a steady-state study, the pressure head boundary condition in the Richards equation module was disabled, the soil elastic-plastic constitutive model was divided into equivalent units using the Comsol finite element software, and the initial moisture field w0, initial stress field σ0, and initial displacement field S0 in the fill were obtained by setting the initial state; S22. Analysis of displacement field under the influence of drainage pipe infiltration: Set the total time of drainage pipe leakage and the output time step, enable the pressure head boundary condition, set the dependent variable to the initial state water field w0, initial stress field σ0 and initial displacement field S0 as the initial value of the seepage state for analysis, and calculate the moisture field w1, stress field σ1 and displacement field S1 of the high fill foundation after humidification in the soil under different compaction degrees and different pipe leakage conditions through the seepage module; S23. Analysis of displacement field after seepage stabilization in drainage pipes: The total time and output time step of the settlement stabilization process are set, and the pressure head boundary condition is disabled. The dependent variables are set to the moisture field w1, stress field σ1, and the last solution of the displacement field S1 is set to the initial value of the stable state for analysis. The surface settlement stabilization process of loess high fill after infiltration of the drainage pipe is simulated. The moisture field w2, stress field σ2, and displacement field S2 in the soil body of the high fill foundation are calculated through the seepage module after the moisture in the drainage pipe no longer seeps out.

7. The method for predicting wetting and settlement of loess high fill induced by pipeline water seepage according to claim 1 is characterized in that: In S2, based on numerical analysis, the variation law of humidification and precipitation under different pipeline leakage conditions is obtained, including: Variations of moisture and displacement fields in high fill foundations at different pipeline leakage locations; Variations of moisture and displacement fields in high fill foundations under different numbers of pipeline leakage points; Variations of water and displacement fields in high fill foundation under different water pressures in pipes; Variation of moisture and displacement fields in high fill foundation under different pipeline diameters; The variation law of moisture field and displacement field of high fill foundation under different pipeline burial depths; The variation law of moisture field and displacement field of high fill foundation under different fill compaction degrees.

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