覆盖型岩溶地基注浆处理与效果检测分析

Grouting treatment of foundation in covered karst region and effect detection analysis

覆盖型岩溶对建筑地基与建筑自身的安全影响较大,结合某实际工程,分析了地基岩溶的发育情况以及溶洞和土洞发育的形态和规模;根据建筑物的基础形式,采用充填浅部溶洞、裂隙和所有土洞的注浆处理方案,以阻断岩溶发育的通道,挤密加固地基土,提高地基承载力。为保证注浆的有效性和经济性,采用由外向内的逐层封闭的注浆方法;采用动态施工技术,根据检测孔的测试结果动态调整施工技术参数。施工完成后对地基进行了物探、检查孔、室内试验、平板载荷试验、标准贯入试验以及沉降观测等。结果表明:对岩溶地基注浆处理的加固效果较为显著,注浆后地基土强度、密度、变形等指标提高幅度为6.4%~25.58%;基于静载荷试验和标准贯入试验结果分析,地基承载力提高大于10%;与桩基础方案和大面积深部溶洞处理方法相比,造价节约20%~30%,工期缩短约1/3。

In the covered karst region, karst cave has a great influence on safety of the building foundation. In this study, combining a practical projection, the development situation of karst is analyzed, and shape and scale of the karst cave are clarified. Based on the form of building foundation, grouting treatment on shallow karst caves and fissure is determined, and bearing capacity of foundation can be improved by filling all soil caves to limit development of karst, and strengthening foundation soil. For practical purposes, grouting is carried out from external to inner of the building foundation, and grouting parameters are dynamically adjusted according to the test results of the detection holes. After completion of grouting, geophysical prospecting, detection hole, indoor test, plate loading test, standard penetration test and long-term settlement observation on building are used to evaluate grouting effect. After grouting, strength, soil intensity and deformation of foundation are increased by 6.4% to 25.58% , and bearing capacity of foundation can be increased by more than 10% according to the results of static load test and standard penetration test, suggesting that reinforcing effect of grouting method in foundation treatment is obvious and remarkable. Compared to pile foundation treatment and treatment on a deep karst with large area, grouting in foundation treatment can save 20% to 30% of total cost of construction, and shorten 1/3 of total construction time.