GROUND BORNE VIBRATION MONITORING DUE TO CONSTRUCTION ACTIVITIES

Ground vibration monitoring using a Geo-phone

Ground borne vibration is a technical term basically used to describe mostly man-made vibrations of the ground, in contrast to natural vibrations of the Earth studied by seismology. Vibrations caused by mining, blasting activities, construction works (in foundation work and heavy machinery movement), railway and road traffic, machinery and plants operating in industries, etc. are falling under this category.It was recognized that, though the manmade ground vibrations can be severe and damaging, the levels of the ground strain involved usually much smaller than those associated with the strong motion of earthquakes. 

A considerable ground born vibration induces during the construction work. And becomes annoying for the neighboring communities. Hence the governments and the different engineering or policy making bodies of countries around world has introduce and certain limits for ground borne vibration and noise generates in construction works. International Standards Organization (ISO), British Standards Institute (BSI) UK are some of the organizations implementing standards or limits for vibration control in construction activities in the world.

Effect of Ground Borne Vibration on Buildings

Generally, type of foundation, ground condition underlying, condition of the building affects the response of a building to ground borne vibration.  Interaction between ground and the foundation of the building has a major effect on building response. The soil condition or the soil layers between the vibration source and the building also can affect the input frequency spectrum to the building. 

Permisable Limits of Ground Borne Vibration due to Constructon Activities 

Table 1: Categorization of structures according to the type of building (from ISO-4966: 1990E)

Category of the structure	Description
Type 1	Multi story buildings of reinforced concrete or structural steel, with in filling panels of block work, brick work or precast units not designed to resist earthquakes
Type 2	Two-story domestic houses & buildings constructed of reinforced block work, precast units, and with reinforced floor & roof construction, or wholly of reinforced concepts or similar, not designed to resist earthquakes
Type 3	Single and two-story houses & buildings made of lighter construction, using lightweight materials such as bricks, cement blocks etc., not designed to resist earthquakes
Type 4	Structures that, because of their sensitivity to vibration, do not correspond to those listed above 1,2 & 3, & declared as archeologically preserved structures by the Department of Archaeology

 Table 2.: Tolerable limits of vibration

Category of the structure as given in Table 1	Type of Vibration	Frequency of Vibration (Hz)	Vibration in PPV (mm/Sec.)
Type 1	Continues	0 -10	5.0
		10 - 50	7.5
		Over 50	15.0
	Intermittent	0 -10	10.0
		10 - 50	15.0
		Over 50	30.0
Type 2	Continues	0 -10	2.0
		10 - 50	4.0
		Over 50	8.0
	Intermittent	0 -10	4.0
		10 - 50	8.0
		Over 50	16.0
Type 3	Continues	0 -10	1.0
		10 - 50	2.0
		Over 50	4.0
	Intermittent	0 -10	2.0
		10 - 50	4.0
		Over 50	8.0
Type 4	Continues	0 -10	0.25
		10 - 50	0.5
		Over 50	1.0
	Intermittent	0 -10	0.5
		10 - 50	1.0
		Over 50	2.0