Design And Construction Control Of Deep Foundation Pit Supporting In Expansive Soil

Expansive soil is a special soil with two significant characteristics: swelling and shrinkage. Because of the changes in soil moisture content and soil swelling pressure difference, soil stress is distributed, leading to problems of safety engineering, which is a worldwide problem in civil engineering. Due to its wide distribution, expansive soil is inevitable to engineering construction. Although retaining and protection measures are taken to ensure foundation excavation, underground structure and surrounding environment, safe and reliable foundation pit support is particularly important when the excavation is too deep and surrounding environment is comparatively complex. With a real example of Pingdingshan 12-meter-deep foundation pit supporting engineering, this article provides analytical research and discussion about the control of expansive soil swelling force and foundation pit excavation, the effect evaluation on surrounding buildings settlement analysis and expansive soil supporting lining construction process quality control method.The main works in this paper are as follows:(1) Review and analyze domestic and abroad materials about expansive soil slope and foundation pit development process of expansion. It is concluded that the swelling soil foundation pit support design is affected by the engineering practice and understanding of unceasingly and more rational development trend. Hence, the expansion soil area foundation pit support design should be prepared with full collectable experience and analysis work of the area so that construction will be safe,economical and convenient.(2) Adapting the strong-pile-weak-anchor support structure is an effective measure to control unexpected expansion force, and has remarkable effect on controlling the deformation of foundation pit and protecting the stability of surrounding buildings.(3) According to the relative importance of the surrounding buildings, using the structure of double row pile anchor support is also a very important and reliablemeasure.(4) Strengthening of process quality control of foundation pit excavation support construction, especially excavation process of prestressd anchor into holes and grouting and shotcrete support control measures, ensures the safety of the foundation pit and the surrounding buildings, and provides certain theoretical and practical basis for the expansion of the land area of the follow-up excavation supporting engineering design.