Reinforcement range determination method for highway roadbed complex goaf construction

Abstract

The invention provides a reinforcement range determination method for highway roadbed complex goaf construction, which comprises the steps of geological investigation and evaluation, stability evaluation, reinforcement range determination, monitoring and evaluation. The method for determining the goaf processing range based on finite element numerical simulation systematically and comprehensively considers the actual displacement monitoring result, has certain accuracy and safety, and can be widely applied to the field of goaf processing.

Description

Technical Field

[0001] The present invention relates to a method for determining the reinforcement range in the construction of a complex goaf area of a highway subgrade, which is applicable to the field of goaf treatment. Background Art

[0002] With the acceleration of the urbanization process and the continuous increase in transportation demands, the construction of highways has played an important role in promoting economic development and improving traffic conditions. However, during the construction of highways, complex geological conditions, especially the foundation problems in goaf areas, pose severe challenges to the stability and safety of subgrades. Goaf areas are usually formed by the extraction of underground mineral resources, and these cavities may lead to surface settlement, deformation, and other instability phenomena, thus affecting the structural safety of highways.

[0003] In the construction of highway subgrades, how to effectively identify and evaluate the impact of goaf areas and then determine a reasonable reinforcement range is the key to ensuring the safety of subgrades and extending their service life. Traditional reinforcement methods often rely on experience and simple evaluations, lacking systematicness and scientificity, which may lead to insufficient or excessive reinforcement measures, resulting in waste of resources and economic losses. Therefore, there is an urgent need for a method for determining the reinforcement range based on scientific analysis to achieve more accurate and effective reinforcement in the construction of complex goaf areas. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem that there is an urgent need for a method for determining the reinforcement range in the construction of highway subgrades on goaf areas based on scientific analysis. A method for determining the reinforcement range in the construction of a complex goaf area of a highway subgrade is proposed.

[0005] The purpose of the present invention can be achieved by adopting the following technical solutions:

[0006] A method for determining the reinforcement range in the construction of a complex goaf area of a highway subgrade, the steps are as follows:

[0007] S101, geological exploration and evaluation;

[0008] The geological exploration and evaluation include carrying out detailed investigation work on the complex goaf area involved in the construction of the highway subgrade. The detailed investigation includes investigating the distribution, size, shape, and lithology of the overlying rock strata in the involved complex goaf area.

[0009] S102, stability evaluation;

[0010] The stability evaluation includes classifying the obtained goafs according to the specific location of the highway line, into Class A goafs and Class B goafs. Class A goafs require stability evaluation of the goaf, while Class B goafs do not require stability evaluation of the goaf;

[0011] The stability evaluation includes conducting stability evaluation work on the Class A goafs to obtain stability evaluation results. The stability evaluation results include that the displacement within the horizontal X meters and vertical Z meters of the highway subgrade side line just exceeds the displacement limit;

[0012] S103, determination of the reinforcement range;

[0013] The determination of the reinforcement range includes determining that the Class A goafs involved within the horizontal X meters and vertical Z meters of the highway subgrade side line according to the stability evaluation results are the reinforcement range, and carrying out goaf reinforcement construction work according to the determined reinforcement range;

[0014] S104, monitoring and evaluation;

[0015] The monitoring and evaluation includes, after completing the goaf reinforcement construction work and the highway subgrade construction work, monitoring the deformation and settlement of the highway subgrade to evaluate the goaf reinforcement effect, and timely feeding back the evaluation results to the later maintenance work.

[0016] Further, in the above S102, the steps of the goaf classification method are as follows: a) Mark the n goafs obtained from geological exploration and evaluation as C1 to C n , b) Obtain the distance L1 between the goaf edge and the highway design edge line, c) Obtain the highway subgrade width L2, d) When the L1 of the goaf C i (i = 1 to n) is less than or equal to the threshold ε, the goaf C i (i = 1 to n) is classified as Class A, otherwise it is Class B.

[0017] Even further, the method for obtaining the threshold ε is to use the calculation formula (1),

[0018] ε = ηL2 (1)

[0019] In the formula, η is a coefficient related to the geology, with a value of 10 to 20, and a smaller value is taken when the geological conditions are better.

[0020] Further, in the above S102, the steps for obtaining the stability evaluation result are as follows: a) Conduct displacement monitoring on the part including the gob area of type A and the highway subgrade for a period of time to obtain the displacement monitoring result; b) Determine the relevant rock parameters of the gob area and the highway subgrade based on the displacement back analysis method according to the displacement monitoring result; c) Establish an analysis model using finite element software according to the relevant rock parameters. The analysis model consists of the gob area of type A, the highway subgrade, and the nearby rocks. In the analysis model, the extension direction of the highway subgrade is the longitudinal direction, the direction perpendicular to the extension direction of the highway subgrade is the transverse direction, and the gravity direction is the vertical direction; d) Apply the most unfavorable load to the highway subgrade of the analysis model according to the actual load-bearing situation of the highway; e) Use the analysis model to conduct displacement analysis to obtain the displacement analysis result; f) Determine the displacement limit value according to the engineering situation and relevant specifications; g) Combine the displacement limit value and the displacement analysis result to determine that the displacement just exceeds the displacement limit value within the range of X meters in the transverse direction and Z meters in the vertical direction of the highway subgrade side line, which is the stability evaluation result.

[0021] The present invention has the following beneficial effects: Based on a comprehensive understanding of the distribution, size, shape, and lithology of the overlying strata of the gob area, the gob area is reasonably classified. In particular, a reasonable quantitative standard for classification is proposed. This quantitative standard takes into account both the properties of the strata and the distance between the gob area and the road, and thus can accurately determine the range of the gob area that needs to be reinforced, avoiding waste of resources caused by over-reinforcement and ensuring the stability of the subgrade. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a flowchart of a method for determining the reinforcement range of a complex gob area in a highway subgrade construction according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The following is a detailed description of the specific embodiments of the present invention with reference to the accompanying drawings; it should be understood that the specific embodiments given here are only for explaining and illustrating the present invention and cannot be used to limit the present invention.

[0024] The following is a specific embodiment of a method for determining the reinforcement range of a complex gob area in a highway subgrade construction.

[0025] The tunnel construction project relied on by this embodiment is: the construction project of the goaf area of a certain section of the Jiaozuo to Pingdingshan Expressway from Xingyang to Xinmi. The geological conditions of the project are that it is located in a river valley plain with relatively flat terrain. There are local cement roads and village roads crossing the red line, and the construction road traffic is relatively convenient; the climate conditions are that it belongs to the northern temperate continental climate, with warm spring, dry and droughty weather, hot summer, rainy and prone to waterlogging, changeable weather in autumn, alternating drought and floods, cold and windy winter, dry with little rain and snow, and frequent winter droughts; the geological lithology is from top to bottom: Cenozoic (Q) silty clay and pebbles, Mesozoic (P1s) mudstone, shale, carbonaceous shale, Carboniferous (C3t) mudstone, shale, carbonaceous shale, and the occurrence of the coal seam in the goaf is 8°∠9° (that is, the dip is 8° southwest and the dip angle is 9°).

[0026] Combination Figure 1 As shown, a method for determining the reinforcement range of a highway roadbed complex goaf area construction of the present invention comprises the following steps:

[0027] S101, Geological Survey and Assessment;

[0028] The geological survey and assessment includes a detailed investigation of the complex goaf areas involved in the highway subgrade construction, and the detailed investigation includes an investigation of the distribution, size, shape and lithology of the overlying rock formations of the goaf areas involved in the complex goaf areas;

[0029] In this embodiment, a survey was conducted on the goaf area of a certain section of the Jiaozuo-Pingdingshan Expressway from Xingyang to Xinmi, and the survey method steps used were: the first step was to collect relevant geological, topographic and geomorphological data of the area, especially the distribution of nearby mineral deposits, mining plans and other information, to preliminarily explore the situation; the second step was to conduct an investigation based on the on-site conditions (mainly to see whether there is a large amount of water on site) using appropriate geophysical means; the third step was drilling verification, through the description of the phenomena of drill drop, drill sticking, flushing fluid leakage, orifice suction and the degree of core fragmentation during the drilling process, to verify the scope of the goaf collapse and judge the development characteristics of the overburden.

[0030] S102, stability evaluation;

[0031] The stability evaluation includes classifying the obtained goaf areas into Class A goaf areas and Class B goaf areas according to the specific location of the high-speed highway line. Class A goaf areas need to be evaluated for stability, while Class B goaf areas do not need to be evaluated for stability.

[0032] The stability evaluation includes performing stability evaluation on the Class A goaf to obtain stability evaluation results, wherein the stability evaluation results include that the displacement within the horizontal range of X meters and the vertical range of Z meters of the highway embankment edge line just exceeds the displacement limit;

[0033] Further, in the above S102, the steps of the goaf classification method are as follows: a) Mark the n goafs obtained from geological exploration and assessment as C1 to C n , b) Obtain the distance L1 between the edge of the goaf and the designed edge line of the highway, c) Obtain the width L2 of the highway subgrade, d) When the L1 of the goaf C i (i = 1 to n) is less than or equal to the threshold ε, the goaf C i (i = 1 to n) is classified as class A, otherwise it is class B.

[0034] Furthermore, the method for obtaining the threshold ε is to use the calculation formula (1),

[0035] ε = ηL2 (1)

[0036] In the formula, η is a coefficient related to geology, and its value ranges from 10 to 20. When the geological condition is good, the value is smaller.

[0037] Further, in the above S102, the steps for obtaining the stability evaluation result are as follows: a) Conduct displacement monitoring on the part including the class A goaf and the highway subgrade for a period of time to obtain the displacement monitoring result, b) Determine the relevant rock parameters of the goaf and the highway subgrade based on the displacement back analysis method according to the displacement monitoring result, c) Establish an analysis model using finite element software according to the relevant rock parameters. The analysis model consists of the class A goaf, the highway subgrade, and the nearby rocks. In the analysis model, the longitudinal direction is the extension direction of the highway subgrade, the transverse direction is perpendicular to the extension direction of the highway subgrade, and the gravity direction is the vertical direction, d) Apply the most unfavorable load to the highway subgrade of the analysis model according to the actual load-bearing situation of the highway, e) Use the analysis model to conduct displacement analysis to obtain the displacement analysis result, f) Determine the displacement limit value according to the engineering situation and relevant specifications, g) Combine the displacement limit value and the displacement analysis result to determine that the displacement within X meters in the transverse direction and Z meters in the vertical direction of the highway subgrade side just exceeds the displacement limit value, which is the stability evaluation result.

[0038] Further, in this embodiment, the value of the threshold ε determined according to the method is 150. The class A goaf is determined according to this threshold, and the stability evaluation result is obtained based on this. When obtaining the stability evaluation result, the displacement back analysis parameters of the analysis model are as shown in Table 1, and the displacement limit values adopted are as shown in Table 2.

[0039] Table 1 Back analysis parameters of the analysis model

[0040]

[0041]

[0042] S103, Determination of the reinforcement scope;

[0043] The determination of the reinforcement scope includes determining that the Class A goaf involved within X meters horizontally and Z meters vertically from the highway subgrade side line according to the stability evaluation result is the reinforcement scope, and carrying out the goaf reinforcement construction work according to the determined reinforcement scope;

[0044] In this embodiment, for the analysis model established for the goaf, within 32 meters of the highway subgrade side line, the ground deformation within a depth of 52 meters just exceeds the ground control index of the expressway. Therefore, the reinforcement scope (which can also be called the treatment scope) is determined as the goaf within 32 meters of the expressway subgrade side line and with a depth of more than 52 meters.

[0045] S104, Monitoring and evaluation;

[0046] The monitoring and evaluation includes, after completing the goaf reinforcement construction work and the highway subgrade construction work, monitoring the deformation and settlement of the highway subgrade, evaluating the goaf reinforcement effect, and timely feeding back the evaluation result to the later maintenance work.

[0047] In the above embodiment, the present invention discloses a method for determining the reinforcement scope of a complex goaf in a highway subgrade, including geological investigation and evaluation, stability evaluation, determination of the reinforcement scope, and monitoring and evaluation. This method proposes a systematic method for determining the goaf treatment scope based on finite element numerical simulation by comprehensively considering the actual displacement monitoring results, which has a certain degree of accuracy and safety and can be widely applied to the field of goaf treatment.

[0048] The above is the preferred embodiment of the present invention and does not limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for determining the reinforcement range in the construction of a complex goaf in the subgrade of an expressway, characterized in that, It includes the following steps: S101 Geological exploration and assessment; The geological exploration and assessment include carrying out detailed investigation work on the complex goaf areas involved in the construction of the highway subgrade. The detailed investigation includes investigating the distribution, size, shape of the goaf areas in the involved complex goaf areas and the lithology of the overlying rock strata; S103 Stability evaluation; The stability evaluation includes classifying the obtained goaf areas according to the specific location of the highway line into Class A goaf areas and Class B goaf areas. Class A goaf areas need to carry out goaf stability evaluation, and Class B goaf areas do not need to carry out goaf stability evaluation; The stability evaluation includes carrying out stability evaluation work on the Class A goaf areas to obtain stability evaluation results. The stability evaluation results include that the displacement within the horizontal X meters and vertical Z meters of the highway subgrade side line just exceeds the displacement limit value; S103 Determination of the reinforcement range; The determination of the reinforcement range includes determining that the Class A goaf areas involved within the horizontal X meters and vertical Z meters of the highway subgrade side line are the reinforcement range according to the stability evaluation results, and carrying out goaf reinforcement construction work according to the determined reinforcement range; S104 Monitoring and evaluation; The monitoring and evaluation include, after completing the goaf reinforcement construction work and the highway subgrade construction work, monitoring the deformation and settlement of the highway subgrade, evaluating the goaf reinforcement effect, and timely feeding back the evaluation results to the later maintenance work.

2. The method for determining the reinforcement range in the construction of a complex goaf in the subgrade of an expressway according to claim 1, wherein In the above (2), the steps of the goaf classification method are as follows: a) Mark the n goafs obtained from geological exploration and evaluation as C1 to C n , b) Obtain the distance L1 between the edge of the goaf and the designed edge line of the highway, c) Obtain the width L2 of the highway subgrade, d) When the L1 of the goaf C i (i = 1 to n) is less than or equal to the threshold value ε, the goaf C i (i = 1 to n) is classified as type A, otherwise it is type B.

3. The method for determining the reinforcement range in the construction of a complex goaf in the highway subgrade according to claim 2, characterized in that The method for obtaining the threshold ε is to use the calculation formula (1), ε = ηL2 (1) In the formula, η is a coefficient related to geology, and its value ranges from 10 to 20. When the geological conditions are better, the value is smaller.

4. A method for determining the reinforcement range in the construction of a complex goaf in a highway subgrade according to claim 1, characterized in that In the above (2), the steps for obtaining the stability evaluation results are as follows: a) Carry out displacement monitoring on the part including the Class A goaf area and the highway subgrade for a period of time to obtain displacement monitoring results; b) Determine the relevant rock parameters of the goaf area and the highway subgrade based on the displacement back analysis method according to the displacement monitoring results; c) Establish an analysis model using finite element software according to the relevant rock parameters. The analysis model consists of the Class A goaf area, the highway subgrade and the nearby rocks. In the analysis model, the extension direction of the highway subgrade is the longitudinal direction, the direction perpendicular to the extension direction of the highway subgrade is the horizontal direction, and the gravity direction is the vertical direction; d) Apply the most unfavorable load to the highway subgrade of the analysis model according to the actual load-bearing situation of the highway; e) Use the analysis model to carry out displacement analysis to obtain displacement analysis results; f) Determine the displacement limit value according to the engineering situation and relevant specifications; g) Combine the displacement limit value and the displacement analysis results to determine that the displacement within the horizontal X meters and vertical Z meters of the highway subgrade side line just exceeds the displacement limit value, which is the stability evaluation result.

Images