TO: georam and KAM
TO: georam and KAM
(OP)
Hi this is CISGeotechnical:
Regarding the thread that you comment me on Stagnant Water on Fill Layer, lets say you are going to face the problem and have to determine where the water comes from.
What type of analysis and/or tests do you would you suggest?
I am used to face settlement problems and solutions in advance of construction, but once it has started... this is new for me.
I would appreciate your help. Thanks in advance.
CISGeotechnical
Regarding the thread that you comment me on Stagnant Water on Fill Layer, lets say you are going to face the problem and have to determine where the water comes from.
What type of analysis and/or tests do you would you suggest?
I am used to face settlement problems and solutions in advance of construction, but once it has started... this is new for me.
I would appreciate your help. Thanks in advance.
CISGeotechnical





RE: TO: georam and KAM
If the soil was not compacted properly and is sandy, it can be chemically grouted to give it a cohesion component and turn it into a weak sandstone. Another option might be to remove the slab in this area, preload the soil with stacked product, and then re-pour the slab with adequate jointing. A specialty ground modification contractor, such as Hayward-Baker, could install compaction grout columns from the base of the slab to a firm soil layer to transfer slab loads through the weak zone. Grouting tends to be expensive.
RE: TO: georam and KAM
RE: TO: georam and KAM
Is the area built up already ? It may be difficult to dig test pits, if the area has been developed. Another sleuthing work would be to drill a hole and collect the water sample. Also drill another hole, preferable in area where there is no fill, and deeper. Get another water sample. Hope that the second sample is groundwater. If chemical analyses of both samples are similar, likely, the water comes from below. If different, it is from surface. May be simple pH, electrical conductivity , chloride test, etc can do the job.
Thirdly, find out a little history and record for the period between the construction of the fill and now :
- settlement which occurs over time (indicate slow consolidation of clay.... 2m fill is not much additional load and unlikely to cause large settlement if the clay is stiff or hard)
- rainfall information... recent rainfall occurs?
- groundwater record of the area... is it common that water table may go up and ponding the ground surface (because of seasonal rising water table ?)
Lastly.... there may be an expensive way to trace water from the surface (rather than do chemical test). I worked on a dam which leaks, and we put some environmentally friendly dye upstream of the potential leakage area, and trace the colour further downstream of the dam.
Is it important that there is supposed to be no water above the clay ? Is the water kept building up with time ? Is settlement becoming a problem ? Perhaps your solution to use french drain is the most practical way !.
Hope this helps