Beijing Yihai Garden Residential Comunity is located in the east of Science City, Fengtai District. It was originally a sand mining pit with a maximum depth of 22.7m and a general depth of 5-18m. It is then backfilled with construction waste and other miscellaneous soil, which is known as the first pit in Beijing. Vibro-stone column has been used for ground improvement. The construction began on April 25, 1999 and was completed by the end of June 1999. The stratum is deep and miscellaneous land foundation, and the building has a high demand for deformation. Using 75KW vibroflot to do the construction, equilateral triangular pile layout, spacing 1400mm, pile diameter 1000mm. Each building is equipped with 1201 piles, and the piles penetrates the mixed soil into the lower middle coarse sand layer. After ground improvement, the bearing capacity of composite foundation is greater than 350 KPa and the deformation modulus is greater than 25 MPa. One year after the completion of the main structure, the settlement is less than 30mm, and the settlement amount and settlement difference meet the requirements.
Hebei Fengning Pumped-storage Power Station is located on the Luanhe River trunk stream in the northwest of Fengning Manzhuang Autonomous County, Hebei Province. The project is of large scale (I) type, and the grade of the building for bar barrier is 1. It is a composite geomagnetic membrane core rockfill dam with a maximum height of 23.5m. The vibro-stone column project of bar is constructed at the elevation of 1,042.5m, and it goes deep into the sand and gravel layer of 1.0m. The construction began on May 3, 2016 and was completed on September 24, 2016. The vibro-stone column is constructed by "forced" packing method, with 1.5m interval and 1.5m row spacing with isosceles triangle arrangement. The total amount of work is 367,142m. After vibroflotation, the bearing capacity characteristic value of composite foundation is ≥250kPa, the equivalent internal friction angle of composite soil is >30.0°, and the equivalent cohesion of composite soil is >7.25kPa.
Renzonghai Reservoir Power Station is the leading reservoir power station located in the Tianwan River basin with a total storage capacity of 112 million cubic meters. The project scale is large (2) type, the engineering grade is class II, the rockfill dam building grade is class 2. The dam is a rockfill dam with the combination of concrete cut-off wall and geomembrane. The crest elevation is 2,934m, the maximum dam height is about 56m, and the crest length is 830.85m. The 7th floor of the dam foundation is silty loam, with a maximum depth of about 19m, which is malleable to soft plastic, low bearing capacity and deformation modulus. It is liquefied soil, we used vibro-stone column to do the ground improvement. The construction began in May 2005 and completed in January 2006.
Vibro-stone columns were used to improve silt loam and weathered crushed stone. Utilized 75kW and 150kW vibroflots to finish a total of 31,295 piles of vibro-stone column. The pile length is 5-28.5m and the footage is 474,279.1m. The bearing capacity of composite foundation is 240kPa, the average density is less than or equal to 0.30, the deformation modulus is greater than 35MPa, and the internal friction angle φ≥30°. After the Wenchuan earthquake and its aftershocks, the dam has been operating safely for many years.
The project is located in Songyuan City, Jilin Province. The project scale is large (I) type, and the project grade is 1. The retaining dam is a clay homogeneous earth dam with a height of 13.55m. The main stratum is the upper fine sand layer and the lower coarse sand layer. The construction began on June 14, 2009 and was completed on September 10, 2010. The sand of foundation is treated with 75 KW vibro compaction process and used double head and single head vibroflot to compact sand layer. Vibro-stone columns are arranged in equilateral triangle with pile diameter of 0.8m and pile length of 8-16m. Beijing Vibro completed 49802 vibro-stone columns and with the footage of 574466.8m. After ground improvement, the relative density of sandy soil reaches 0.8 and it can resist in a magnitude-8 earthquake and eliminate liquefaction.
