| With the continuous development of infrastructure construction in China,laterite is widely used as an engineering material.Laterite is a brownish-red sticky soil formed by weathering of carbonate rocks such as limestone and dolomite under subtropical warm climate conditions.It is widely distributed in the Yungui Plateau,eastern Sichuan,the two lakes region,and some areas in northern Guangdong and Guangxi.Due to its good engineering characteristics,laterite is commonly used as a building material for foundations,roadbeds,and other engineering construction projects.However,the construction of laterite foundations and roadbeds can cause varying degrees of deformation under permanent load pressure,which requires detailed engineering exploration.As a branch of geophysical exploration,electrical resistivity methods are characterized by continuity,speed,non-destructiveness,and can quickly explore the distribution of internal materials in large-scale and deep engineering projects.The conventional detection technology and post-processing technology in traditional testing engineering are not coordinated,resulting in problems such as time-consuming testing and low efficiency.In contrast,electrical resistivity methods can provide more comprehensive and rapid detection and serve as an indicator for engineering evaluation.Therefore,it is of great significance to explore the electrical resistivity characteristics in the consolidation and compression processes of laterite and establish relevant electrical resistivity prediction models.Furthermore,using electrical resistivity inversion imaging to make reasonable judgments and evaluations of the exploration results in laterite areas is important for practical engineering applications.In order to explore the electrical resistivity characteristics during the consolidation and compression process of laterite,this article prepared laterite soil samples with different dry densities and moisture contents in laboratory experiments.The LCR-4090A type electrical resistivity tester was used to test and record the changes in horizontal and vertical electrical resistivity of the laterite soil samples before and during consolidation and compression.The reasons for changes in electrical resistivity were analyzed,and the feasibility of using electrical resistivity as an indicator for evaluating other parameters was determined.Based on this study,relevant electrical resistivity models were developed,and finally,an evaluation index for electrical resistivity was obtained.The main research conclusions are as follows:(1)As vertical multi-level loads were continuously applied,the vertical and horizontal electrical resistivity,average structure factor,and average shape factor of the laterite all showed a gradual decrease,while the anisotropy coefficient showed a trend of first decreasing,then slowly rising to a stable level.Moreover,there was a quantitative relationship between the comprehensive evaluation index of the laterite’s structural characteristics(E_R)and the compaction degree(K),indicating the feasibility of using this index to evaluate the compactness of the laterite.(2)Under continuous graded loading,the electrical resistivity of laterite decreased with increasing vertical load and saturation degree,and increased with increasing porosity.According to multiple linear regression analysis,the factors that influence electrical resistivity were found to be correlated in the following order:saturation degree,vertical load,and porosity.A laterite prediction model was constructed using feature model fusion analysis,which can effectively evaluate the porosity changes during the consolidation process of laterite.The calculated value of the laterite compression coefficient obtained from this model matched well with the experimental value,indicating the feasibility of using electrical resistivity to evaluate the compression coefficient.(3)Based on the relationship between electrical resistivity and structural characteristics during consolidation testing,taking into account the influence of saturation degree and porosity on electrical resistivity structural characteristics,a laterite compaction evaluation model based on electrical resistivity structural characteristics was established,with high fitting accuracy and small model verification error.The model has good applicability and can provide theoretical reference for the convenient detection of compaction degree in laterite rolling engineering using high-density electrical method.(4)Based on the study of the electrical resistivity theory and its model applicability,an electrical resistivity settlement prediction model was obtained by combining the one-dimensional compression deformation theory formula.The settlement rate error and the comparison between the actual and predicted values of compression coefficient were obtained.The model is reliable and can be used to obtain the quantitative evaluation criteria of the electrical resistivity for the compressibility of undisturbed laterite in practical engineering through relevant specifications.(5)By comparing and analyzing the relevant soil changes and potential changes during the consolidation process with the corresponding experimental values using Comsol software,it was found that the errors were all small,indicating that Comsol software has reliability in demonstrating the various laws and numerical changes during the consolidation process.The electrical resistivity method is an efficient testing method,and the quantification of soil performance indicators based on the electrical resistivity method will be a hot topic and trend in future research.With the deepening exploration of the electrical resistivity characteristics of different types of soil,the establishment and improvement of related prediction models and systems,high-density electrical resistivity testing will obtain high-precision and high-resolution electrical resistivity data,which will provide strong technical support for in-depth understanding of the electrical resistivity structure and characteristics of soil. |
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