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Unsaturated granite residual soils are widely used as compacted soils in engineering structures such as slopes, embankments and backfills. Shear strength of soil are important in many geotechnical problems. A series of unconfined compression tests are carried out on unsaturated residual soils. Furthermore, since the residual soils are impaired in contact with water and have poor water-stable properties, slaking test of residual soil was conducted. Results of tests show effects of moisture content and cyclic wetting and drying on strength. Moisture content of soils is higher than the optimum moisture content of 2% for high strength and it is lower than optimum moisture content of 2% for good plasticity in Xiamen areas. Cyclic wetting and drying causes loss of unconfined compression strength and the maximum loss often occurs at the first cycle and then slowed down till the strength remains constant. In addition, wetting and drying cycles accelerate disintegration speed and shortened the whole disintegration. Soil in small dry density tends more easily to be disintegrated than one in high dry density.

Shenzhen Metro line no.5 is the longest metro line of Shenzhen in one-time investment which met with complex geological conditions, great technical difficulties and short construction period. According to the characteristics of the project, Shenzhen government broke the traditional mindset to use the BT construction model through ' Investment and Financing-Building Delivery with Design and Construction Return' creatively, and built the structure of project management matching the mode. Exploration and innovation of the management mode focused on the integration of design and construction in the construction process of the metro line No.5 have been done by China Railway Group. Under the BT mode, design management phase should be involved early in the project. Meanwhile, effective work should be done such as technical preparation, design schedule, design modification, quality control, safety control and investment control. The construction practice of the Shenzhen Metro line No.5 indicated that the integration of design and construction is good to condense construction period, ensure the safety and quality of project and investment control.