Hello, I thought that this could be interesting problem to share.
A utility trench (almost 50 m long) with depth of 2 m is proposed at horizontal offset of 2 - 3 m from a wall of 3 storeys house . Unfortunately, the wall has been reported to have cracks due to both structural issues and foundation settlement. Horizontal offset between the problematic wall and trench can't be increased. As understood there 2 to 2.5 m of compacted fill overlaying firm to silty clay at subject site. The excavation of trench may compromise the stability of the wall . Conceptual solution options:
First obtain more accurate soil profile at site and information on the depth of the foundation of the wall with respect to depth of the trench. Solution options would be :
1- Lower the burial depth of the utility to the minimum possible (1.5 m ) and if the depth of trench is shallower than the depth of the wall foundation ( wall foundation settlement is not likely to happen). Even with the shallow trench of 1.5 m , structurally support the trench side (soldier timber piles system) without causing any tangible vibration (more than 5 mm/sec) (Utilize experienced excavation contractor)
2-If you can't figure out the depth of the wall foundation or if it is shallower than minimum trench depth (1.5m) , use proper trenchless technique ( that results in minimum gaps between drilled hole and pipe) to install the utility pipe in the subject trench.
3-other option is just fix the problem of the settled wall before excavation of the trench
Your thoughts and discussion on this matter will be appreciated
A utility trench (almost 50 m long) with depth of 2 m is proposed at horizontal offset of 2 - 3 m from a wall of 3 storeys house . Unfortunately, the wall has been reported to have cracks due to both structural issues and foundation settlement. Horizontal offset between the problematic wall and trench can't be increased. As understood there 2 to 2.5 m of compacted fill overlaying firm to silty clay at subject site. The excavation of trench may compromise the stability of the wall . Conceptual solution options:
First obtain more accurate soil profile at site and information on the depth of the foundation of the wall with respect to depth of the trench. Solution options would be :
1- Lower the burial depth of the utility to the minimum possible (1.5 m ) and if the depth of trench is shallower than the depth of the wall foundation ( wall foundation settlement is not likely to happen). Even with the shallow trench of 1.5 m , structurally support the trench side (soldier timber piles system) without causing any tangible vibration (more than 5 mm/sec) (Utilize experienced excavation contractor)
2-If you can't figure out the depth of the wall foundation or if it is shallower than minimum trench depth (1.5m) , use proper trenchless technique ( that results in minimum gaps between drilled hole and pipe) to install the utility pipe in the subject trench.
3-other option is just fix the problem of the settled wall before excavation of the trench
Your thoughts and discussion on this matter will be appreciated
