马街河水库坝基蚀变花岗岩勘察研究及其处理分析

Exploration and treatment analysis of altered granite in dam foundation of Majiehe Reservoir

本文通过物探和地质勘察试验揭示和研究马街河水库坝基蚀变花岗岩的蚀变特征及工程地质特性,进而分析评价水库建坝的主要工程地质问题和处理措施。结果表明:坝基为印支期侵入蚀变花岗岩,全风化岩体呈砂状,力学性质和可灌性差;强—微风化岩体承载力低,岩石饱和单轴抗压强度5.9~39.0MPa,软化系数0.34~0.68,完整性系数0.11~0.69,多属破碎—较破碎岩体;异于同层风化程度的特殊风化体占比较高;岩体渗透性局部不均匀、相对隔水层较深,对坝基稳定和防渗影响较大。依据该结果选择黏土心墙风化料坝、全风化岩体采用孔距加密至1.0m的帷幕灌浆方案,同时对心墙范围内坝基进行固结灌浆。本文对下一步工作也提出了粗浅建议,供类似勘察设计类工程参考。

In this paper,the alteration characteristics and project geological characteristics of the altered granite in the dam foundation of Majiehe Reservoir are revealed and studied through geophysical exploration and geological investigation tests,and then the main project ecological problems and treatment measures of dam construction of the reservoir are analyzed and evaluated.The results show that the dam foundation is Indosinian intrusive altered granite,and the fully weathered rock mass is sandy with poor mechanical properties and groutability.The strongly~slightly weathered rock mass has low bearing capacity,with saturated uniaxial compressive strength of 5.9~39.0MPa,softening coefficient of 0.34~0.68 and integrity coefficient of 0.11~0.69,which are mostly broken~relatively broken rock mass.The proportion of special weathered bodies which is different from the weathered degree of the same layer is high.The rock mass permeability is not uniform and the relative confining bed is deep,which has great influence on the stability and seepage-proofing of dam foundation.According to the results,the curtain grouting scheme with hole pacing of 1.0m is selected for the weathered material dam with clay core wall and fully weathered rock mass.At the same time,the consolidation grouting of the dam foundation within the core wall is carried out.This paper also puts forward some suggestions for the next step,which can be used as reference for similar survey and design projects.