Project

Engineering Condition

Dong Miao residential area was located in the north side of Lvyou Road in Lixia District, Jinan province. The west of the area is the Jingzhuang Mountains. As the strongly-weathered limestone is the bearing directly basic layer, the geographic conditions is more complex. The landscape is hill and the total building area is about 37526㎡.

The mountain has been cut and divided into west slope and east slope because of the engineering construction. The two slopes threaten badly to the project. The slope is mainly composed of a lot of construction wastes and a certain amount of household garbage, which was piled by the people around and remote city. Therefore, the homogeneity of the slope is extremely bad and the slope is even in a loose condition after long-time scour during the rainy season.

The Feature of Construction Method

The traditional deep excavation retaining method can not meet the requirement of the stabilization of large-scale underground buildings. Especially in sandy cobble stratum where the ratio of finishing gas hole is very low, it must lead to high pressure for the grouting and anchoring later and increase the construction cost.

The technique of self drilling anchor bolt, which is introduced from foreign countries, is a new kind of rock-soil anchoring technique to apply for the projects in complicated geological conditions and construction environment especially in the weak soil and sandy cobble stratum.

Engineering Design

This project adopts joint support method including cutting slope & reducing load, self drilling anchor bolt, barricade downhill, and concrete grille. The gradient of the slope is 1:0.8, the angel 50°and unloading earthwork quantity 5500 cubic meters. The vertical height of self drilling anchor bolt is 3 meters, the length between 16~20 meters and the distance on the surface of slope is 4 meters. They are arranged as a plum, and the dip angle is 15°. The total footage of the self drilling anchor bolt is 7320 meters. One thing should be noticed is that the bolts must be installed in the nodal point of the grille in order to be connected with each other as a whole.