Recent Experiences of Reinforced Soil Retaining Structures in China - Reinforced Soil Engineering: Advances in Research and Practice - page 177

4.5 Reinforced Collapsed Soil Retaining Wall

The yellow soil—a kind of collapsed soil—is mainly distributed in the Shanxi
Province located in northwest China. There are a lot of storm cracks, which bring
trouble to road construction. Many dry bridges have to be thrown across these
cracks. Some bridges with a long span are expensive. Three reinforced collapsed
soil retaining walls with heights from 11.1 m to 23.1m have been constructed on
the main highway from Xian to Yanan instead of the dry bridges.

4.5.1 Design and Construction

The walls with a face slope of 1:0.05 have been constructed along two sides of
highway across the storm cracks. The hexagonal concrete panels with a height
of 800mm and a thickness of 100 mm are connected with parawebs made of
polypropylene, whose tensile strength is 4.6 kN per strip and elongation is 6%.
The websoil system is designed taking into considerations both Rankine's theory
of earth pressure and active zone widens 0.3H (H is height of wall). The
compaction degree of backfills is required to reach 93% of r dmax . For the wall
with a height more than 15m, a horizontal platform with a width of 1.25 m should
be designed on the level of H/2. The platform and surface of the road have to be
treated by waterproof materials, such as concrete or asphalt so that the moisture
of backfill soil can be maintained. Otherwise, some drainage ditches should be
arranged along the upslopes to escape the rains.

4.5.2 Cost-Effectiveness

These retaining walls with a total length of 477m were completed in 1989. Their
good quality has been proven by successful transport service. The total
investment was 883,000 yuan compared with the budget of 9,586,000 yuan for
dry bridges (Wang Zhongsheng, 1992).

4.6 Retaining Walls in a Foundation Engineering of Pump
Station

The Zhijiang pump station for drainage of waterlogging with three pumps of
800 kW is on a silty clay foundation in Huibei Province. The underground water
level is very high. When the foundation pit was excavated to a depth of 8m in
November 1993, the severe piping prohibited further excavation. The pit had to
be moved a width of foundation apart from the Yangtze River. The former pit
should be filled and three concrete pipes with an inner diameter of 2m had to put
on a high compacted soil. In order to prevent the cracks of pipes caused by
settlement of filled clay, the added design plan was construction of six “p-type”
concrete frames and 6

£ 4 ¼ 24 piles to sustain pipes. Another problem was that