SOIL INVESTIGATION
(Based on Marina Barrage Project experience)

BRIEF
The commonly used field tests to gauge soil strength include Standard Penetration Test (SPT, numbers of blow to achieve 300mm penetration using 63.5kg hammer at 760mm free drop), Vane Shear Test (VST, to estimate the undrained shear strength of the soil) and Cone Penetration Test (CPT, to estimate cone resistance and local friction with the pore water pressure). Pressuremeter Test is to estimate the compressibility characteristics. For ground water permeability, there is Field Permeability Test.

The laboratory tests involve sampling from boreholes and subsequently testing for physical, mechanical and chemical properties.

Laboratory soil physical properties test consists of:
- Moisture content
- bulk and dry density
- Atterberg limits (Liquid Limit, Plastic Limit)
- Particle size distribution

Laboratory mechanical properties test consists of:
- Unconsolidated undrained triaxial (UU)
- Consolidated undrained triaxial (CU)
- Oedometer consolidation test

Laboratory chemical and toxicity tests are to identify hazardous materials including pH value, sulphate (SO3), organic content, etc.

LAND CPT
CPT (Cone Penetration Test) is the field soil investigation to determine the soil shear strength and strata layers by pressing the rod (about 1.2' diameter with cone at its end) to the soil. The entire equipment including the recording computer CPT is installed on a 20 ton medium weight, track mounted caterpillar tracks. The penetrometer system is a self propelled hydraulic controlled CPT system.


Crawler mounted land CPT, with integrated equipment inside


A rod with cone at the end to be pressed into soil


Field computer is recording and analysing the data

MARINE CPT
CPT test conducted at sea


Marine CPT

PLATE LOADING TEST
To find out the existing ground whether a mobile / crawler crane is safe to move on it. A steel plate measuring 300mm diameter is put on the ground and then apply pressure of approximately 300 kPa (100 x safety factor 3.0), using excavator as the reaction load (about 10t).


Plate loading test


INSTRUMENTATION AND MONITORING
(Based on Marina Barrage Project experience)

Before deep excavation, soil instrumentation must be installed strategically to monitor soil movement and surrounding properties and services. Typical instrumentation includes inclinometer (horizontal displacement), water standpipe (ground water table), piezometer (ground water pores pressure) and settlement markers (ground settlement).


Install inclinometer, water standpipe and piezometer - standard cluster at one place, using "A" frame


Initializing the inclinometer before taking reading


Taking readings from an inclinometer


Taking readings from a piezometer


TERMINOLOGIES

Type of Load
- SWL: Specified Working Load
- ULS: Ultimate Limit State
- SLS: Serviceable Limit State

In-Situ Test
- CPT: Cone penetration test
- DMT: Flat dilatometer test
- FVT: Field vane test
- PMT: Pressuremeter test
- SPT: Standard penetration test
- Permeability test

Laboratory Test
- CU: Consolidated-undrained test
- UU: Unconsolidated-undrained test
- CD: Consolidated-drained test