Bearing Capacity from CPT Data Spreadsheet

It is possible to estimate a soil's bearing capacity from CPT data. The Soil Bearing Capacity from SI Info Spreadsheet Suite includes a design spreadsheet which uses the procedure detailed in BS 8004 to estimate the bearing capacity of the soil from CPT test results. This is particularly useful in granular soils where undisturbed soil design parameters can be difficult to ascertain.

This spreadsheet is included within the Soil Bearing Capacity from SI Info Spreadsheet Suite which can be purchased at the bottom of this page for just £10. Alternatively the full CivilWeb Soil Bearing Capacity Calculation Excel Suite including 9 different methods including the CPT data method can be purchased together for just £20.

Cone Penetration Test (CPT)

The Cone Penetration Test has become popular in both Europe and North America in recent years. This test allows the properties of the soil to be determined at depth without taking samples. Empirical correlations between the CPT results and soil properties and even bearing capacity directly are available.

The Cone Penetration Test or CPT is a static site investigation test used to investigate the properties of soils without taking samples. This test is commonly undertaken on medium sands, soft silts and clays. The test involves pushing a standard sized steel cone into the soil at a constant rate. The force required to do this is measured throughout the test which provides an insight into the strength and properties of the soils. The test procedure is described in BS 1377 Part 9 and ASTM D-3441.

CPT Bearing Capacity Correlations

Many correlations have been proposed to relate soil properties to CPT test results. These include angle of shearing strength, undrained shear strength and compressibility. These empirical relationships can be used to estimate the bearing capacity and settlement of a foundation in these soils.

The CivilWeb Spreadsheet uses a method included in BS 8004 as the basis for a bearing capacity calculator based on CPT results. This method is particularly useful in granular soils where it can be very difficult or even impossible for undisturbed samples of the soil to be taken for laboratory analysis. In these cases analytical bearing capacity calculation methods are not reliable and site investigation data such as CPT results is more reliable.

Bearing Capacity from CPT Data - Inputs

The spreadsheet requires the designer to input some details from the CPT results in order to estimate the bearing capacity of the soil. These details include the shape and size of the proposed foundation, the stress applied by the foundation, the density of the soil and the q_c values at different soil depths.

The spreadsheet uses this data to calculate both the allowable bearing capacity of the soil and the expected settlement of the foundation. The spreadsheet includes unique analysis tools which allow the designer to see at a glance the effects of different sized foundations, different foundation depths and different applied stresses will have on the soil. This allows the designer to optimise the design in minutes without having to repeat time consuming iterative calculations by hand.

CivilWeb Bearing Capacity from CPT Data Spreadsheet

The CivilWeb Bearing Capacity from CPT Data Spreadsheet can be used to estimate the bearing capacity of a soil using the results of a CPT test. This is particularly useful for granular soils. This powerful design spreadsheet includes unique optimisation tools allowing the designer to complete a fully optimised bearing capacity calculation from CPT data in minutes without time consuming hand calculations. The CivilWeb Bearing Capacity from CPT Data Spreadsheet is included in the Soil Bearing Capacity from SI Info spreadsheet.