**Introduction:**

The Hiley formula is a widely used method for calculating the required number of piles in a foundation. The formula was developed by R.L. Hiley and is based on the principle of load transfer from a superstructure to the underlying soil. In this article, we will discuss the Hiley formula, its derivation, and its application in pile set calculation.

## Derivation of the Hiley Formula

The Hiley formula is derived from the theory of elasticity and assumes that the soil behaves as an elastic material. According to this theory, the load applied to a foundation is transferred to the soil through the piles. The load transfer mechanism can be represented by the following equation:

Q = Ap + Ks

Where Q is the load transmitted to the soil, A is the area of the pile, p is the pressure acting on the pile, K is the coefficient of subgrade reaction, and s is the deflection of the pile.

The Hiley formula is based on the assumption that the load transmitted to the soil is proportional to the deflection of the pile. Therefore, we can **rewrite the above equation as follows:**

Q = K’s^2

Where K’ is the proportionality constant known as the coefficient of proportionality or the Hiley constant.

**The Hiley constant can be calculated using the following equation:**

K’ = (PA) / L^3

Where P is the ultimate load capacity of the pile, A is the area of the pile, and L is the length of the pile.

### Calculation of Pile Set Using the Hiley Formula

Once the Hiley constant is determined, we can use it to calculate the required number of piles in a foundation. The pile set calculation involves the following steps:

Determine the loads acting on the foundation. This includes the weight of the superstructure, the live loads, and any other loads that may be acting on the foundation.

Determine the soil characteristics such as the bearing capacity, soil type, and soil properties.

**Calculate the required pile capacity using the following equation:**

Preq = Qtotal / N

Where Preq is the required pile capacity, Qtotal is the total load acting on the foundation, and N is the number of piles.

Calculate the Hiley constant using the equation mentioned earlier.

**Calculate the required number of piles using the following equation:**

Nreq = (Qtotal / K’s^2)^(1/3)

Where Nreq is the required number of piles, Qtotal is the total load acting on the foundation, and K’ is the Hiley constant.

### How is pile set calculated?

Pile set is calculated by determining the loads acting on the foundation, such as the weight of the superstructure, live loads, and any other loads that may be acting on the foundation. The soil characteristics such as the bearing capacity, soil type, and soil properties are also determined. The required pile capacity is then calculated using appropriate formulae and the required number of piles is calculated using the Hiley formula or other relevant formulas.

### How do you calculate the number of piles?

The number of piles is calculated by dividing the total load acting on the foundation by the ultimate capacity of a single pile. This gives the minimum number of piles required to support the structure. However, other factors such as the spacing of the piles, the arrangement of the piles, and the soil conditions may require a higher number of piles.

### What is the formula for height of pile?

The formula for the height of a pile is not standard and depends on various factors such as the load capacity of the pile, the soil characteristics, and the design requirements of the project. However, a general formula for the length of a pile can be given as L = (Qs + Qu) / σc.Af where L is the length of the pile, Qs is the working load on the pile, Qu is the ultimate load on the pile, σc is the permissible stress in concrete, and Af is the cross-sectional area of the pile.

### What is the Gates formula for pile capacity?

The Gates formula is an empirical formula used to estimate the safe load-carrying capacity of driven piles in sands and clays. The formula is given as follows Q = Apu + Kpu.L where Q is the allowable load capacity of the pile, A is the cross-sectional area of the pile, pu is the unit skin friction resistance along the pile, L is the length of the pile, and Kp is the coefficient of end-bearing resistance.

Hiley formula pile set calculation spreadsheet A Hiley formula pile set calculation spreadsheet is a tool that can help engineers and designers to calculate the required number of piles in a foundation using the Hiley formula. The spreadsheet typically contains input fields for the loads acting on the foundation and the soil characteristics, as well as output fields for the required pile capacity and the required number of piles.

Hiley formula excel The Hiley formula can be implemented in Excel using appropriate formulae and functions. Engineers and designers can create an Excel sheet with input fields for the loads acting on the foundation and the soil characteristics, and use Excel’s mathematical functions to calculate the required pile capacity and the required number of piles based on the Hiley formula.

Temporary compression of pile Temporary compression of a pile refers to the short-term settlement of the pile under load due to elastic deformation of the soil surrounding the pile. This phenomenon is usually observed during the initial stages of loading and disappears once the excess pore pressures dissipate. The amount of temporary compression depends on various factors such as the stiffness of the soil, the size and shape of the pile, and the magnitude and duration of the load.

### What is the Hiley formula?

The Hiley formula is a method for calculating the required number of piles in a foundation based on the principle of load transfer from a superstructure to the underlying soil. It assumes that the load transmitted to the soil is proportional to the deflection of the pile and uses a proportionality constant known as the Hiley constant to calculate the required number of piles.

### How is the Hiley constant calculated?

The Hiley constant can be calculated using the equation K’ = (PA) / L^3, where P is the ultimate load capacity of the pile, A is the cross-sectional area of the pile, and L is the length of the pile.

### What is pile set calculation?

Pile set calculation involves determining the required number of piles in a foundation to support the loads acting on the structure. This includes calculating the required pile capacity and using the Hiley formula or other relevant formulas to calculate the required number of piles.

### How do you calculate the required pile capacity?

The required pile capacity is calculated by dividing the total load acting on the foundation by the ultimate capacity of a single pile. Other factors such as the spacing of the piles, the arrangement of the piles, and the soil conditions may require a higher number of piles.

### What is the Gates formula for pile capacity?

The Gates formula is an empirical formula used to estimate the safe load-carrying capacity of driven piles in sands and clays. It takes into account the unit skin friction resistance along the pile and the coefficient of end-bearing resistance.

### What is the role of soil properties in pile set calculations?

Soil properties such as bearing capacity, soil type, and soil stiffness affect the load transfer mechanism between the superstructure and the underlying soil. These properties are considered when calculating the required number of piles and their design parameters.

### How can spreadsheets and Excel be used in pile set calculations?

Spreadsheets and Excel can be used to create tools for pile set calculations, with input fields for loads and soil properties, and output fields for required pile capacity and the required number of piles based on the Hiley formula or other relevant formulas.

### What is temporary compression of a pile?

Temporary compression of a pile refers to the short-term settlement of the pile under load due to elastic deformation of the soil surrounding the pile. This phenomenon is usually observed during the initial stages of loading and disappears once the excess pore pressures dissipate.

## Conclusion:

The Hiley formula provides a simple and efficient method for calculating the required number of piles in a foundation. The formula is based on the principle of load transfer from a superstructure to the underlying soil and is derived from the theory of elasticity. By using the Hiley formula, engineers can design cost-effective and safe foundations that meet the requirements of the project.